Sell bets (#12)

* sell bet

* dev mode

* single-pot no-refund payoff; bet selling

* Increase default fetch size 25 -> 99

* Fix about page numbering

* Don't flash no markets when loading on tag page.

* Change Title to use body font

* Make a bunch of predictions at once (#9)

* Set up a page to make bulk predictions

* Integrate preview into the same card

* List created predictions

* Make changes per James's comments

* Increase the starting balance (#11)

* Remove references to paying for our Mantic Dollars

* Update simulator to use new calculations

* Change simulator random to be evenly random again

* Sell bet UI

* Migrate contracts and bets script

* Add comment to script

* bets => trades; exclude sold bets

* change sale formula

* Change current value to uncapped sell value.

* Disable sell button while selling

* Update some 'bet' to 'trade'

Co-authored-by: Austin Chen <akrolsmir@gmail.com>
Co-authored-by: jahooma <jahooma@gmail.com>

.firebaserc

@@ -1,5 +1,7 @@
 {
   "projects": {
-    "default": "mantic-markets"
+    "default": "mantic-markets",
+    "prod": "mantic-markets",
+    "dev": "dev-mantic-markets"
   }
 }

functions/package.json

@@ -2,6 +2,7 @@
   "name": "functions",
   "scripts": {
     "build": "tsc",
+    "watch": "tsc -w",
     "serve": "yarn build && firebase emulators:start --only functions",
     "shell": "yarn build && firebase functions:shell",
     "start": "yarn shell",

functions/src/index.ts

@@ -2,6 +2,7 @@ import * as admin from 'firebase-admin'
 
 admin.initializeApp()
 
-export * from './keep-awake'
+// export * from './keep-awake'
 export * from './place-bet'
 export * from './resolve-market'
+export * from './sell-bet'

functions/src/place-bet.ts

@@ -43,7 +43,7 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
         .collection(`contracts/${contractId}/bets`)
         .doc()
 
-      const { newBet, newPool, newDpmWeights, newBalance } = getNewBetInfo(
+      const { newBet, newPool, newTotalShares, newBalance } = getNewBetInfo(
         user,
         outcome,
         amount,
@@ -54,7 +54,7 @@ export const placeBet = functions.runWith({ minInstances: 1 }).https.onCall(
       transaction.create(newBetDoc, newBet)
       transaction.update(contractDoc, {
         pool: newPool,
-        dpmWeights: newDpmWeights,
+        totalShares: newTotalShares,
       })
       transaction.update(userDoc, { balance: newBalance })
 
@@ -79,29 +79,19 @@ const getNewBetInfo = (
       ? { YES: yesPool + amount, NO: noPool }
       : { YES: yesPool, NO: noPool + amount }
 
-  const dpmWeight =
+  const shares =
     outcome === 'YES'
-      ? (amount * noPool ** 2) / (yesPool ** 2 + amount * yesPool)
+      ? amount + (amount * noPool ** 2) / (yesPool ** 2 + amount * yesPool)
-      : (amount * yesPool ** 2) / (noPool ** 2 + amount * noPool)
+      : amount + (amount * yesPool ** 2) / (noPool ** 2 + amount * noPool)
 
-  const { YES: yesWeight, NO: noWeight } = contract.dpmWeights || {
+  const { YES: yesShares, NO: noShares } = contract.totalShares
-    YES: 0,
-    NO: 0,
-  } // only nesc for old contracts
 
-  const newDpmWeights =
+  const newTotalShares =
     outcome === 'YES'
-      ? { YES: yesWeight + dpmWeight, NO: noWeight }
+      ? { YES: yesShares + shares, NO: noShares }
-      : { YES: yesWeight, NO: noWeight + dpmWeight }
+      : { YES: yesShares, NO: noShares + shares }
 
   const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
-
-  const probAverage =
-    (amount +
-      noPool * Math.atan(yesPool / noPool) -
-      noPool * Math.atan((amount + yesPool) / noPool)) /
-    amount
-
   const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2)
 
   const newBet: Bet = {
@@ -109,15 +99,14 @@ const getNewBetInfo = (
     userId: user.id,
     contractId: contract.id,
     amount,
-    dpmWeight,
+    shares,
     outcome,
     probBefore,
-    probAverage,
     probAfter,
     createdTime: Date.now(),
   }
 
   const newBalance = user.balance - amount
 
-  return { newBet, newPool, newDpmWeights, newBalance }
+  return { newBet, newPool, newTotalShares, newBalance }
 }

functions/src/resolve-market.ts

@@ -78,22 +78,27 @@ export const resolveMarket = functions
 const firestore = admin.firestore()
 
 const getPayouts = (outcome: string, contract: Contract, bets: Bet[]) => {
-  const [yesBets, noBets] = _.partition(bets, (bet) => bet.outcome === 'YES')
+  const openBets = bets.filter((b) => !b.isSold && !b.sale)
+  const [yesBets, noBets] = _.partition(
+    openBets,
+    (bet) => bet.outcome === 'YES'
+  )
 
-  const [pool, winningBets] =
+  const startPool = contract.startPool.YES + contract.startPool.NO
+  const truePool = contract.pool.YES + contract.pool.NO - startPool
+
+  const [totalShares, winningBets] =
     outcome === 'YES'
-      ? [contract.pool.NO - contract.startPool.NO, yesBets]
+      ? [contract.totalShares.YES, yesBets]
-      : [contract.pool.YES - contract.startPool.YES, noBets]
+      : [contract.totalShares.NO, noBets]
 
-  const finalPool = (1 - PLATFORM_FEE - CREATOR_FEE) * pool
+  const finalPool = (1 - PLATFORM_FEE - CREATOR_FEE) * truePool
-  const creatorPayout = CREATOR_FEE * pool
+  const creatorPayout = CREATOR_FEE * truePool
   console.log('final pool:', finalPool, 'creator fee:', creatorPayout)
 
-  const sumWeights = _.sumBy(winningBets, (bet) => bet.dpmWeight)
-
   const winnerPayouts = winningBets.map((bet) => ({
     userId: bet.userId,
-    payout: bet.amount + (bet.dpmWeight / sumWeights) * finalPool,
+    payout: (bet.shares / totalShares) * finalPool,
   }))
 
   return winnerPayouts.concat([

functions/src/scripts/migrate-contract.ts

@@ -0,0 +1,58 @@
+import * as admin from 'firebase-admin'
+import * as _ from 'lodash'
+import { Bet } from '../types/bet'
+import { Contract } from '../types/contract'
+
+type DocRef = admin.firestore.DocumentReference
+
+// Generate your own private key, and set the path below:
+// https://console.firebase.google.com/u/0/project/mantic-markets/settings/serviceaccounts/adminsdk
+const serviceAccount = require('../../../../Downloads/mantic-markets-firebase-adminsdk-1ep46-820891bb87.json')
+
+admin.initializeApp({
+  credential: admin.credential.cert(serviceAccount),
+})
+const firestore = admin.firestore()
+
+async function migrateBet(contractRef: DocRef, bet: Bet) {
+  const { dpmWeight, amount, id } = bet as Bet & { dpmWeight: number }
+  const shares = dpmWeight + amount
+
+  await contractRef.collection('bets').doc(id).update({ shares })
+}
+
+async function migrateContract(contractRef: DocRef, contract: Contract) {
+  const bets = await contractRef
+    .collection('bets')
+    .get()
+    .then((snap) => snap.docs.map((bet) => bet.data() as Bet))
+
+  const totalShares = {
+    YES: _.sumBy(bets, (bet) => (bet.outcome === 'YES' ? bet.shares : 0)),
+    NO: _.sumBy(bets, (bet) => (bet.outcome === 'NO' ? bet.shares : 0)),
+  }
+
+  await contractRef.update({ totalShares })
+}
+
+async function migrateContracts() {
+  console.log('Migrating contracts')
+
+  const snapshot = await firestore.collection('contracts').get()
+  const contracts = snapshot.docs.map((doc) => doc.data() as Contract)
+
+  console.log('Loaded contracts', contracts.length)
+
+  for (const contract of contracts) {
+    const contractRef = firestore.doc(`contracts/${contract.id}`)
+    const betsSnapshot = await contractRef.collection('bets').get()
+    const bets = betsSnapshot.docs.map((bet) => bet.data() as Bet)
+
+    console.log('contract', contract.question, 'bets', bets.length)
+
+    for (const bet of bets) await migrateBet(contractRef, bet)
+    await migrateContract(contractRef, contract)
+  }
+}
+
+if (require.main === module) migrateContracts().then(() => process.exit())

functions/src/sell-bet.ts

@@ -0,0 +1,162 @@
+import * as admin from 'firebase-admin'
+import * as functions from 'firebase-functions'
+
+import { CREATOR_FEE, PLATFORM_FEE } from './resolve-market'
+import { Bet } from './types/bet'
+import { Contract } from './types/contract'
+import { User } from './types/user'
+
+export const sellBet = functions.runWith({ minInstances: 1 }).https.onCall(
+  async (
+    data: {
+      contractId: string
+      betId: string
+    },
+    context
+  ) => {
+    const userId = context?.auth?.uid
+    if (!userId) return { status: 'error', message: 'Not authorized' }
+
+    const { contractId, betId } = data
+
+    // run as transaction to prevent race conditions
+    return await firestore.runTransaction(async (transaction) => {
+      const userDoc = firestore.doc(`users/${userId}`)
+      const userSnap = await transaction.get(userDoc)
+      if (!userSnap.exists)
+        return { status: 'error', message: 'User not found' }
+      const user = userSnap.data() as User
+
+      const contractDoc = firestore.doc(`contracts/${contractId}`)
+      const contractSnap = await transaction.get(contractDoc)
+      if (!contractSnap.exists)
+        return { status: 'error', message: 'Invalid contract' }
+      const contract = contractSnap.data() as Contract
+
+      const betDoc = firestore.doc(`contracts/${contractId}/bets/${betId}`)
+      const betSnap = await transaction.get(betDoc)
+      if (!betSnap.exists) return { status: 'error', message: 'Invalid bet' }
+      const bet = betSnap.data() as Bet
+
+      if (bet.isSold) return { status: 'error', message: 'Bet already sold' }
+
+      const newBetDoc = firestore
+        .collection(`contracts/${contractId}/bets`)
+        .doc()
+
+      const { newBet, newPool, newTotalShares, newBalance, creatorFee } =
+        getSellBetInfo(user, bet, contract, newBetDoc.id)
+
+      const creatorDoc = firestore.doc(`users/${contract.creatorId}`)
+      const creatorSnap = await transaction.get(creatorDoc)
+      if (creatorSnap.exists) {
+        const creator = creatorSnap.data() as User
+        const creatorNewBalance = creator.balance + creatorFee
+        transaction.update(creatorDoc, { balance: creatorNewBalance })
+      }
+
+      transaction.update(betDoc, { isSold: true })
+      transaction.create(newBetDoc, newBet)
+      transaction.update(contractDoc, {
+        pool: newPool,
+        totalShares: newTotalShares,
+      })
+      transaction.update(userDoc, { balance: newBalance })
+
+      return { status: 'success' }
+    })
+  }
+)
+
+const firestore = admin.firestore()
+
+const getSellBetInfo = (
+  user: User,
+  bet: Bet,
+  contract: Contract,
+  newBetId: string
+) => {
+  const { id: betId, amount, shares, outcome } = bet
+
+  const { YES: yesPool, NO: noPool } = contract.pool
+  const { YES: yesStart, NO: noStart } = contract.startPool
+  const { YES: yesShares, NO: noShares } = contract.totalShares
+
+  const [y, n, s] = [yesPool, noPool, shares]
+
+  const shareValue =
+    outcome === 'YES'
+      ? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
+        (n ** 2 +
+          s * y +
+          y ** 2 -
+          Math.sqrt(
+            n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
+          )) /
+        (2 * y)
+      : (y ** 2 +
+          s * n +
+          n ** 2 -
+          Math.sqrt(
+            y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
+          )) /
+        (2 * n)
+
+  const startPool = yesStart + noStart
+  const pool = yesPool + noPool - startPool
+
+  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
+
+  const f = pool / (probBefore * yesShares + (1 - probBefore) * noShares)
+
+  const myPool = outcome === 'YES' ? yesPool - yesStart : noPool - noStart
+
+  const adjShareValue = Math.min(Math.min(1, f) * shareValue, myPool)
+
+  const newPool =
+    outcome === 'YES'
+      ? { YES: yesPool - adjShareValue, NO: noPool }
+      : { YES: yesPool, NO: noPool - adjShareValue }
+
+  const newTotalShares =
+    outcome === 'YES'
+      ? { YES: yesShares - shares, NO: noShares }
+      : { YES: yesShares, NO: noShares - shares }
+
+  const probAfter = newPool.YES ** 2 / (newPool.YES ** 2 + newPool.NO ** 2)
+
+  const creatorFee = CREATOR_FEE * adjShareValue
+  const saleAmount = (1 - CREATOR_FEE - PLATFORM_FEE) * adjShareValue
+
+  console.log(
+    'SELL M$',
+    amount,
+    outcome,
+    'for M$',
+    saleAmount,
+    'M$/share:',
+    f,
+    'creator fee: M$',
+    creatorFee
+  )
+
+  const newBet: Bet = {
+    id: newBetId,
+    userId: user.id,
+    contractId: contract.id,
+    amount: -adjShareValue,
+    shares: -shares,
+    outcome,
+    probBefore,
+    probAfter,
+    createdTime: Date.now(),
+    sale: {
+      amount: saleAmount,
+      betId,
+    },
+  }
+
+  const newBalance = user.balance + saleAmount
+
+  return { newBet, newPool, newTotalShares, newBalance, creatorFee }
+}

functions/src/types/bet.ts

@@ -2,11 +2,20 @@ export type Bet = {
   id: string
   userId: string
   contractId: string
-  amount: number // Amount of bet
+
-  outcome: 'YES' | 'NO' // Chosen outcome
+  amount: number // bet size; negative if SELL bet
-  createdTime: number
+  outcome: 'YES' | 'NO'
+  shares: number // dynamic parimutuel pool weight; negative if SELL bet
+
   probBefore: number
-  probAverage: number
   probAfter: number
-  dpmWeight: number // Dynamic Parimutuel weight
+
+  sale?: {
+    amount: number // amount user makes from sale
+    betId: string // id of bet being sold
+  }
+
+  isSold?: boolean // true if this BUY bet has been sold
+
+  createdTime: number
 }

functions/src/types/contract.ts

@@ -12,7 +12,7 @@ export type Contract = {
 
   startPool: { YES: number; NO: number }
   pool: { YES: number; NO: number }
-  dpmWeights: { YES: number; NO: number }
+  totalShares: { YES: number; NO: number }
 
   createdTime: number // Milliseconds since epoch
   lastUpdatedTime: number // If the question or description was changed

web/components/bet-panel.tsx

@@ -12,9 +12,9 @@ import { formatMoney, formatPercent } from '../lib/util/format'
 import { Title } from './title'
 import {
   getProbability,
-  getDpmWeight,
+  calculateShares,
   getProbabilityAfterBet,
-} from '../lib/calculation/contract'
+} from '../lib/calculate'
 import { firebaseLogin } from '../lib/firebase/users'
 
 export function BetPanel(props: { contract: Contract; className?: string }) {
@@ -84,9 +84,9 @@ export function BetPanel(props: { contract: Contract; className?: string }) {
     betChoice,
     betAmount ?? 0
   )
-  const dpmWeight = getDpmWeight(contract.pool, betAmount ?? 0, betChoice)
+  const shares = calculateShares(contract.pool, betAmount ?? 0, betChoice)
 
-  const estimatedWinnings = Math.floor((betAmount ?? 0) + dpmWeight)
+  const estimatedWinnings = Math.floor(shares)
   const estimatedReturn = betAmount
     ? (estimatedWinnings - betAmount) / betAmount
     : 0
@@ -98,7 +98,7 @@ export function BetPanel(props: { contract: Contract; className?: string }) {
     <Col
       className={clsx('bg-gray-100 shadow-xl px-8 py-6 rounded-md', className)}
     >
-      <Title className="!mt-0 whitespace-nowrap" text="Place a bet" />
+      <Title className="!mt-0 whitespace-nowrap" text="Place a trade" />
 
       <div className="mt-2 mb-1 text-sm text-gray-400">Outcome</div>
       <YesNoSelector
@@ -107,7 +107,7 @@ export function BetPanel(props: { contract: Contract; className?: string }) {
         onSelect={(choice) => onBetChoice(choice)}
       />
 
-      <div className="mt-3 mb-1 text-sm text-gray-400">Bet amount</div>
+      <div className="mt-3 mb-1 text-sm text-gray-400">Amount</div>
       <Col className="my-2">
         <label className="input-group">
           <span className="text-sm bg-gray-200">M$</span>
@@ -168,18 +168,18 @@ export function BetPanel(props: { contract: Contract; className?: string }) {
           )}
           onClick={betDisabled ? undefined : submitBet}
         >
-          {isSubmitting ? 'Submitting...' : 'Place bet'}
+          {isSubmitting ? 'Submitting...' : 'Submit trade'}
         </button>
       ) : (
         <button
           className="btn mt-4 border-none normal-case text-lg font-medium px-10 bg-gradient-to-r from-teal-500 to-green-500 hover:from-teal-600 hover:to-green-600"
           onClick={firebaseLogin}
         >
-          Sign in to bet!
+          Sign in to trade!
         </button>
       )}
 
-      {wasSubmitted && <div className="mt-4">Bet submitted!</div>}
+      {wasSubmitted && <div className="mt-4">Trade submitted!</div>}
     </Col>
   )
 }

web/components/bets-list.tsx

@@ -13,10 +13,13 @@ import { Row } from './layout/row'
 import { UserLink } from './user-page'
 import {
   calculatePayout,
+  calculateSaleAmount,
   currentValue,
   resolvedPayout,
-} from '../lib/calculation/contract'
+} from '../lib/calculate'
 import clsx from 'clsx'
+import { cloudFunction } from '../lib/firebase/api-call'
+import { ConfirmationButton } from './confirmation-button'
 
 export function BetsList(props: { user: User }) {
   const { user } = props
@@ -65,19 +68,26 @@ export function BetsList(props: { user: User }) {
     contracts,
     (contract) => contract.isResolved
   )
+
   const currentBets = _.sumBy(unresolved, (contract) =>
-    _.sumBy(contractBets[contract.id], (bet) => bet.amount)
+    _.sumBy(contractBets[contract.id], (bet) => {
+      if (bet.isSold || bet.sale) return 0
+      return bet.amount
+    })
   )
 
   const currentBetsValue = _.sumBy(unresolved, (contract) =>
-    _.sumBy(contractBets[contract.id], (bet) => currentValue(contract, bet))
+    _.sumBy(contractBets[contract.id], (bet) => {
+      if (bet.isSold || bet.sale) return 0
+      return currentValue(contract, bet)
+    })
   )
 
   return (
     <Col className="mt-6 gap-6">
       <Row className="gap-8">
         <Col>
-          <div className="text-sm text-gray-500">Active bets</div>
+          <div className="text-sm text-gray-500">Currently invested</div>
           <div>{formatMoney(currentBets)}</div>
         </Col>
         <Col>
@@ -173,16 +183,17 @@ export function MyBetsSummary(props: {
   const { bets, contract, className } = props
   const { resolution } = contract
 
-  const betsTotal = _.sumBy(bets, (bet) => bet.amount)
+  const excludeSales = bets.filter((b) => !b.isSold && !b.sale)
+  const betsTotal = _.sumBy(excludeSales, (bet) => bet.amount)
 
   const betsPayout = resolution
     ? _.sumBy(bets, (bet) => resolvedPayout(contract, bet))
     : 0
 
-  const yesWinnings = _.sumBy(bets, (bet) =>
+  const yesWinnings = _.sumBy(excludeSales, (bet) =>
     calculatePayout(contract, bet, 'YES')
   )
-  const noWinnings = _.sumBy(bets, (bet) =>
+  const noWinnings = _.sumBy(excludeSales, (bet) =>
     calculatePayout(contract, bet, 'NO')
   )
 
@@ -190,7 +201,7 @@ export function MyBetsSummary(props: {
     <Row className={clsx('gap-4 sm:gap-6', className)}>
       <Col>
         <div className="text-sm text-gray-500 whitespace-nowrap">
-          Total bets
+          Amount invested
         </div>
         <div className="whitespace-nowrap">{formatMoney(betsTotal)}</div>
       </Col>
@@ -228,6 +239,11 @@ export function ContractBetsTable(props: {
 }) {
   const { contract, bets, className } = props
 
+  const [sales, buys] = _.partition(bets, (bet) => bet.sale)
+  const salesDict = _.fromPairs(
+    sales.map((sale) => [sale.sale?.betId ?? '', sale])
+  )
+
   const { isResolved } = contract
 
   return (
@@ -237,15 +253,21 @@ export function ContractBetsTable(props: {
           <tr className="p-2">
             <th>Date</th>
             <th>Outcome</th>
-            <th>Bet</th>
+            <th>Amount</th>
             <th>Probability</th>
             {!isResolved && <th>Est. max payout</th>}
             <th>{isResolved ? <>Payout</> : <>Current value</>}</th>
+            <th></th>
           </tr>
         </thead>
         <tbody>
-          {bets.map((bet) => (
+          {buys.map((bet) => (
-            <BetRow key={bet.id} bet={bet} contract={contract} />
+            <BetRow
+              key={bet.id}
+              bet={bet}
+              sale={salesDict[bet.id]}
+              contract={contract}
+            />
           ))}
         </tbody>
       </table>
@@ -253,14 +275,22 @@ export function ContractBetsTable(props: {
   )
 }
 
-function BetRow(props: { bet: Bet; contract: Contract }) {
+function BetRow(props: { bet: Bet; contract: Contract; sale?: Bet }) {
-  const { bet, contract } = props
+  const { bet, sale, contract } = props
-  const { amount, outcome, createdTime, probBefore, probAfter, dpmWeight } = bet
+  const {
+    amount,
+    outcome,
+    createdTime,
+    probBefore,
+    probAfter,
+    shares,
+    isSold,
+  } = bet
   const { isResolved } = contract
 
   return (
     <tr>
-      <td>{dayjs(createdTime).format('MMM D, H:mma')}</td>
+      <td>{dayjs(createdTime).format('MMM D, h:mma')}</td>
       <td>
         <OutcomeLabel outcome={outcome} />
       </td>
@@ -268,18 +298,63 @@ function BetRow(props: { bet: Bet; contract: Contract }) {
       <td>
         {formatPercent(probBefore)} → {formatPercent(probAfter)}
       </td>
-      {!isResolved && <td>{formatMoney(amount + dpmWeight)}</td>}
+      {!isResolved && <td>{formatMoney(shares)}</td>}
       <td>
-        {formatMoney(
+        {bet.isSold
-          isResolved
+          ? 'N/A'
-            ? resolvedPayout(contract, bet)
+          : formatMoney(
-            : currentValue(contract, bet)
+              isResolved
-        )}
+                ? resolvedPayout(contract, bet)
+                : bet.sale
+                ? bet.sale.amount ?? 0
+                : currentValue(contract, bet)
+            )}
       </td>
+
+      {sale ? (
+        <td>SOLD for {formatMoney(Math.abs(sale.amount))}</td>
+      ) : (
+        !isResolved &&
+        !isSold && (
+          <td className="text-neutral">
+            <SellButton contract={contract} bet={bet} />
+          </td>
+        )
+      )}
     </tr>
   )
 }
 
+const sellBet = cloudFunction('sellBet')
+
+function SellButton(props: { contract: Contract; bet: Bet }) {
+  const { contract, bet } = props
+  const [isSubmitting, setIsSubmitting] = useState(false)
+
+  return (
+    <ConfirmationButton
+      id={`sell-${bet.id}`}
+      openModelBtn={{
+        className: clsx('btn-sm', isSubmitting && 'btn-disabled loading'),
+        label: 'Sell',
+      }}
+      submitBtn={{ className: 'btn-primary' }}
+      onSubmit={async () => {
+        setIsSubmitting(true)
+        await sellBet({ contractId: contract.id, betId: bet.id })
+        setIsSubmitting(false)
+      }}
+    >
+      <div className="text-2xl mb-4">Sell</div>
+      <div>
+        Do you want to sell your {formatMoney(bet.amount)} position on{' '}
+        <OutcomeLabel outcome={bet.outcome} /> for{' '}
+        {formatMoney(calculateSaleAmount(contract, bet))}?
+      </div>
+    </ConfirmationButton>
+  )
+}
+
 function OutcomeLabel(props: { outcome: 'YES' | 'NO' | 'CANCEL' }) {
   const { outcome } = props
 

web/components/contract-overview.tsx

@@ -90,7 +90,7 @@ export const ContractOverview = (props: {
 }) => {
   const { contract, className } = props
   const { resolution, creatorId } = contract
-  const { probPercent, volume } = compute(contract)
+  const { probPercent, truePool } = compute(contract)
 
   const user = useUser()
   const isCreator = user?.id === creatorId
@@ -140,7 +140,7 @@ export const ContractOverview = (props: {
       <ContractDescription contract={contract} isCreator={isCreator} />
 
       {/* Show a delete button for contracts without any trading */}
-      {isCreator && volume === 0 && (
+      {isCreator && truePool === 0 && (
         <>
           <Spacer h={8} />
           <button

web/components/contracts-list.tsx

@@ -17,7 +17,7 @@ import { Linkify } from './linkify'
 
 export function ContractDetails(props: { contract: Contract }) {
   const { contract } = props
-  const { volume, createdDate, resolvedDate } = compute(contract)
+  const { truePool, createdDate, resolvedDate } = compute(contract)
 
   return (
     <Row className="flex-wrap text-sm text-gray-500">
@@ -29,7 +29,7 @@ export function ContractDetails(props: { contract: Contract }) {
         {resolvedDate ? `${createdDate} - ${resolvedDate}` : createdDate}
       </div>
       <div className="mx-2">•</div>
-      <div className="whitespace-nowrap">{formatMoney(volume)} volume</div>
+      <div className="whitespace-nowrap">{formatMoney(truePool)} pool</div>
     </Row>
   )
 }
@@ -110,14 +110,14 @@ function ContractsGrid(props: { contracts: Contract[] }) {
   )
 }
 
-type Sort = 'createdTime' | 'volume' | 'resolved' | 'all'
+type Sort = 'createdTime' | 'pool' | 'resolved' | 'all'
 export function SearchableGrid(props: {
   contracts: Contract[]
   defaultSort?: Sort
 }) {
   const { contracts, defaultSort } = props
   const [query, setQuery] = useState('')
-  const [sort, setSort] = useState(defaultSort || 'volume')
+  const [sort, setSort] = useState(defaultSort || 'pool')
 
   function check(corpus: String) {
     return corpus.toLowerCase().includes(query.toLowerCase())
@@ -132,8 +132,8 @@ export function SearchableGrid(props: {
 
   if (sort === 'createdTime' || sort === 'resolved' || sort === 'all') {
     matches.sort((a, b) => b.createdTime - a.createdTime)
-  } else if (sort === 'volume') {
+  } else if (sort === 'pool') {
-    matches.sort((a, b) => compute(b).volume - compute(a).volume)
+    matches.sort((a, b) => compute(b).truePool - compute(a).truePool)
   }
 
   if (sort !== 'all') {
@@ -159,7 +159,7 @@ export function SearchableGrid(props: {
           value={sort}
           onChange={(e) => setSort(e.target.value as Sort)}
         >
-          <option value="volume">Most traded</option>
+          <option value="pool">Most traded</option>
           <option value="createdTime">Newest first</option>
           <option value="resolved">Resolved</option>
           <option value="all">All markets</option>

web/components/profile-menu.tsx

@@ -41,8 +41,8 @@ function getNavigationOptions(user: User, options: { mobile: boolean }) {
         ]
       : []),
     {
-      name: 'Your bets',
+      name: 'Your trades',
-      href: '/bets',
+      href: '/trades',
     },
     {
       name: 'Your markets',
@@ -64,7 +64,7 @@ function ProfileSummary(props: { user: User }) {
       <div className="rounded-full w-10 h-10 mr-4">
         <Image src={user.avatarUrl} width={40} height={40} />
       </div>
-      <div className="truncate" style={{ maxWidth: 175 }}>
+      <div className="truncate text-left" style={{ maxWidth: 175 }}>
         {user.name}
         <div className="text-gray-700 text-sm">{formatMoney(user.balance)}</div>
       </div>

web/lib/calculate.ts

@@ -0,0 +1,134 @@
+import { Bet } from './firebase/bets'
+import { Contract } from './firebase/contracts'
+
+const fees = 0.02
+
+export function getProbability(pool: { YES: number; NO: number }) {
+  const [yesPool, noPool] = [pool.YES, pool.NO]
+  const numerator = Math.pow(yesPool, 2)
+  const denominator = Math.pow(yesPool, 2) + Math.pow(noPool, 2)
+  return numerator / denominator
+}
+
+export function getProbabilityAfterBet(
+  pool: { YES: number; NO: number },
+  outcome: 'YES' | 'NO',
+  bet: number
+) {
+  const [YES, NO] = [
+    pool.YES + (outcome === 'YES' ? bet : 0),
+    pool.NO + (outcome === 'NO' ? bet : 0),
+  ]
+  return getProbability({ YES, NO })
+}
+
+export function calculateShares(
+  pool: { YES: number; NO: number },
+  bet: number,
+  betChoice: 'YES' | 'NO'
+) {
+  const [yesPool, noPool] = [pool.YES, pool.NO]
+
+  return betChoice === 'YES'
+    ? bet + (bet * noPool ** 2) / (yesPool ** 2 + bet * yesPool)
+    : bet + (bet * yesPool ** 2) / (noPool ** 2 + bet * noPool)
+}
+
+export function calculatePayout(
+  contract: Contract,
+  bet: Bet,
+  outcome: 'YES' | 'NO' | 'CANCEL'
+) {
+  const { amount, outcome: betOutcome, shares } = bet
+
+  if (outcome === 'CANCEL') return amount
+  if (betOutcome !== outcome) return 0
+
+  const { totalShares } = contract
+
+  if (totalShares[outcome] === 0) return 0
+
+  const startPool = contract.startPool.YES + contract.startPool.NO
+  const pool = contract.pool.YES + contract.pool.NO - startPool
+
+  return (1 - fees) * (shares / totalShares[outcome]) * pool
+}
+
+export function resolvedPayout(contract: Contract, bet: Bet) {
+  if (contract.resolution)
+    return calculatePayout(contract, bet, contract.resolution)
+  throw new Error('Contract was not resolved')
+}
+
+export function currentValue(contract: Contract, bet: Bet) {
+  // const prob = getProbability(contract.pool)
+  // const yesPayout = calculatePayout(contract, bet, 'YES')
+  // const noPayout = calculatePayout(contract, bet, 'NO')
+
+  // return prob * yesPayout + (1 - prob) * noPayout
+
+  const { shares, outcome } = bet
+
+  const { YES: yesPool, NO: noPool } = contract.pool
+  const [y, n, s] = [yesPool, noPool, shares]
+
+  const shareValue =
+    outcome === 'YES'
+      ? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
+        (n ** 2 +
+          s * y +
+          y ** 2 -
+          Math.sqrt(
+            n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
+          )) /
+        (2 * y)
+      : (y ** 2 +
+          s * n +
+          n ** 2 -
+          Math.sqrt(
+            y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
+          )) /
+        (2 * n)
+
+  return (1 - fees) * shareValue
+}
+export function calculateSaleAmount(contract: Contract, bet: Bet) {
+  const { shares, outcome } = bet
+
+  const { YES: yesPool, NO: noPool } = contract.pool
+  const { YES: yesStart, NO: noStart } = contract.startPool
+  const { YES: yesShares, NO: noShares } = contract.totalShares
+
+  const [y, n, s] = [yesPool, noPool, shares]
+
+  const shareValue =
+    outcome === 'YES'
+      ? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
+        (n ** 2 +
+          s * y +
+          y ** 2 -
+          Math.sqrt(
+            n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
+          )) /
+        (2 * y)
+      : (y ** 2 +
+          s * n +
+          n ** 2 -
+          Math.sqrt(
+            y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
+          )) /
+        (2 * n)
+
+  const startPool = yesStart + noStart
+  const pool = yesPool + noPool - startPool
+
+  const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
+  const f = pool / (probBefore * yesShares + (1 - probBefore) * noShares)
+
+  const myPool = outcome === 'YES' ? yesPool - yesStart : noPool - noStart
+
+  const adjShareValue = Math.min(Math.min(1, f) * shareValue, myPool)
+
+  const saleAmount = (1 - fees) * adjShareValue
+  return saleAmount
+}

web/lib/calculation/contract.ts

@@ -1,72 +0,0 @@
-import { Bet } from '../firebase/bets'
-import { Contract } from '../firebase/contracts'
-
-const fees = 0.02
-
-export function getProbability(pool: { YES: number; NO: number }) {
-  const [yesPool, noPool] = [pool.YES, pool.NO]
-  const numerator = Math.pow(yesPool, 2)
-  const denominator = Math.pow(yesPool, 2) + Math.pow(noPool, 2)
-  return numerator / denominator
-}
-
-export function getProbabilityAfterBet(
-  pool: { YES: number; NO: number },
-  outcome: 'YES' | 'NO',
-  bet: number
-) {
-  const [YES, NO] = [
-    pool.YES + (outcome === 'YES' ? bet : 0),
-    pool.NO + (outcome === 'NO' ? bet : 0),
-  ]
-  return getProbability({ YES, NO })
-}
-
-export function getDpmWeight(
-  pool: { YES: number; NO: number },
-  bet: number,
-  betChoice: 'YES' | 'NO'
-) {
-  const [yesPool, noPool] = [pool.YES, pool.NO]
-
-  return betChoice === 'YES'
-    ? (bet * Math.pow(noPool, 2)) / (Math.pow(yesPool, 2) + bet * yesPool)
-    : (bet * Math.pow(yesPool, 2)) / (Math.pow(noPool, 2) + bet * noPool)
-}
-
-export function calculatePayout(
-  contract: Contract,
-  bet: Bet,
-  outcome: 'YES' | 'NO' | 'CANCEL'
-) {
-  const { amount, outcome: betOutcome, dpmWeight } = bet
-
-  if (outcome === 'CANCEL') return amount
-  if (betOutcome !== outcome) return 0
-
-  let { dpmWeights, pool, startPool } = contract
-
-  // Fake data if not set.
-  if (!dpmWeights) dpmWeights = { YES: 100, NO: 100 }
-
-  // Fake data if not set.
-  if (!pool) pool = { YES: 100, NO: 100 }
-
-  const otherOutcome = outcome === 'YES' ? 'NO' : 'YES'
-  const poolSize = pool[otherOutcome] - startPool[otherOutcome]
-
-  return (1 - fees) * (dpmWeight / dpmWeights[outcome]) * poolSize + amount
-}
-export function resolvedPayout(contract: Contract, bet: Bet) {
-  if (contract.resolution)
-    return calculatePayout(contract, bet, contract.resolution)
-  throw new Error('Contract was not resolved')
-}
-
-export function currentValue(contract: Contract, bet: Bet) {
-  const prob = getProbability(contract.pool)
-  const yesPayout = calculatePayout(contract, bet, 'YES')
-  const noPayout = calculatePayout(contract, bet, 'NO')
-
-  return prob * yesPayout + (1 - prob) * noPayout
-}

web/lib/firebase/api-call.ts

@@ -0,0 +1,6 @@
+import { getFunctions, httpsCallable } from 'firebase/functions'
+
+const functions = getFunctions()
+
+export const cloudFunction = (name: string) => httpsCallable(functions, name)
+

web/lib/firebase/bets.ts

@@ -11,12 +11,21 @@ export type Bet = {
   id: string
   userId: string
   contractId: string
-  amount: number // Amount of bet
+
-  outcome: 'YES' | 'NO' // Chosen outcome
+  amount: number // bet size; negative if SELL bet
-  dpmWeight: number // Dynamic Parimutuel weight
+  outcome: 'YES' | 'NO'
+  shares: number // dynamic parimutuel pool weight; negative if SELL bet
+
   probBefore: number
-  probAverage: number
   probAfter: number
+
+  sale?: {
+    amount: number // amount user makes from sale
+    betId: string // id of bet being sold
+  }
+
+  isSold?: boolean // true if this BUY bet has been sold
+
   createdTime: number
 }
 

web/lib/firebase/contracts.ts

@@ -30,7 +30,7 @@ export type Contract = {
 
   startPool: { YES: number; NO: number }
   pool: { YES: number; NO: number }
-  dpmWeights: { YES: number; NO: number }
+  totalShares: { YES: number; NO: number }
 
   createdTime: number // Milliseconds since epoch
   lastUpdatedTime: number // If the question or description was changed
@@ -48,7 +48,7 @@ export function path(contract: Contract) {
 
 export function compute(contract: Contract) {
   const { pool, startPool, createdTime, resolutionTime, isResolved } = contract
-  const volume = pool.YES + pool.NO - startPool.YES - startPool.NO
+  const truePool = pool.YES + pool.NO - startPool.YES - startPool.NO
   const prob = pool.YES ** 2 / (pool.YES ** 2 + pool.NO ** 2)
   const probPercent = Math.round(prob * 100) + '%'
   const startProb =
@@ -57,7 +57,7 @@ export function compute(contract: Contract) {
   const resolvedDate = isResolved
     ? dayjs(resolutionTime).format('MMM D')
     : undefined
-  return { volume, probPercent, startProb, createdDate, resolvedDate }
+  return { truePool, probPercent, startProb, createdDate, resolvedDate }
 }
 
 const db = getFirestore(app)

web/lib/firebase/init.ts

@@ -1,24 +1,28 @@
 import { getFirestore } from '@firebase/firestore'
 import { initializeApp } from 'firebase/app'
-const firebaseConfig = {
+
-  apiKey: 'AIzaSyDp3J57vLeAZCzxLD-vcPaGIkAmBoGOSYw',
+export const isProd = process.env.NODE_ENV === 'production'
-  authDomain: 'mantic-markets.firebaseapp.com',
+
-  projectId: 'mantic-markets',
+const firebaseConfig = isProd
-  storageBucket: 'mantic-markets.appspot.com',
+  ? {
-  messagingSenderId: '128925704902',
+      apiKey: 'AIzaSyDp3J57vLeAZCzxLD-vcPaGIkAmBoGOSYw',
-  appId: '1:128925704902:web:f61f86944d8ffa2a642dc7',
+      authDomain: 'mantic-markets.firebaseapp.com',
-  measurementId: 'G-SSFK1Q138D',
+      projectId: 'mantic-markets',
-}
+      storageBucket: 'mantic-markets.appspot.com',
+      messagingSenderId: '128925704902',
+      appId: '1:128925704902:web:f61f86944d8ffa2a642dc7',
+      measurementId: 'G-SSFK1Q138D',
+    }
+  : {
+      apiKey: 'AIzaSyBoq3rzUa8Ekyo3ZaTnlycQYPRCA26VpOw',
+      authDomain: 'dev-mantic-markets.firebaseapp.com',
+      projectId: 'dev-mantic-markets',
+      storageBucket: 'dev-mantic-markets.appspot.com',
+      messagingSenderId: '134303100058',
+      appId: '1:134303100058:web:27f9ea8b83347251f80323',
+      measurementId: 'G-YJC9E37P37',
+    }
 
 // Initialize Firebase
 export const app = initializeApp(firebaseConfig)
 export const db = getFirestore(app)
-
-// try {
-//   // Note: this is still throwing a console error atm...
-//   import('firebase/analytics').then((analytics) => {
-//     analytics.getAnalytics(app)
-//   })
-// } catch (e) {
-//   console.warn('Analytics were blocked')
-// }

web/lib/service/create-contract.ts

@@ -2,7 +2,6 @@ import {
   Contract,
   getContractFromSlug,
   pushNewContract,
-  setContract,
 } from '../firebase/contracts'
 import { User } from '../firebase/users'
 import { randomString } from '../util/random-string'
@@ -38,7 +37,7 @@ export async function createContract(
 
     startPool: { YES: startYes, NO: startNo },
     pool: { YES: startYes, NO: startNo },
-    dpmWeights: { YES: 0, NO: 0 },
+    totalShares: { YES: 0, NO: 0 },
     isResolved: false,
 
     // TODO: Set create time to Firestore timestamp
@@ -49,8 +48,8 @@ export async function createContract(
   return await pushNewContract(contract)
 }
 
-export function calcStartPool(initialProb: number, initialCapital = 200) {
+export function calcStartPool(initialProbInt: number, initialCapital = 200) {
-  const p = initialProb / 100.0
+  const p = initialProbInt / 100.0
 
   const startYes =
     p === 0.5

web/lib/simulator/entries.ts

@@ -21,10 +21,13 @@ function makeWeights(bids: Bid[]) {
   // First pass: calculate all the weights
   for (const { yesBid, noBid } of bids) {
     const yesWeight =
-      (yesBid * Math.pow(noPot, 2)) / (Math.pow(yesPot, 2) + yesBid * yesPot) ||
+      yesBid +
-      0
+        (yesBid * Math.pow(noPot, 2)) /
+          (Math.pow(yesPot, 2) + yesBid * yesPot) || 0
     const noWeight =
-      (noBid * Math.pow(yesPot, 2)) / (Math.pow(noPot, 2) + noBid * noPot) || 0
+      noBid +
+        (noBid * Math.pow(yesPot, 2)) / (Math.pow(noPot, 2) + noBid * noPot) ||
+      0
 
     // Note: Need to calculate weights BEFORE updating pot
     yesPot += yesBid
@@ -53,15 +56,15 @@ export function makeEntries(bids: Bid[]): Entry[] {
   const yesWeightsSum = weights.reduce((sum, entry) => sum + entry.yesWeight, 0)
   const noWeightsSum = weights.reduce((sum, entry) => sum + entry.noWeight, 0)
 
+  const potSize = yesPot + noPot - YES_SEED - NO_SEED
+
   // Second pass: calculate all the payouts
   const entries: Entry[] = []
 
   for (const weight of weights) {
     const { yesBid, noBid, yesWeight, noWeight } = weight
-    // Payout: You get your initial bid back, as well as your share of the
+    const yesPayout = (yesWeight / yesWeightsSum) * potSize
-    // (noPot - seed) according to your yesWeight
+    const noPayout = (noWeight / noWeightsSum) * potSize
-    const yesPayout = yesBid + (yesWeight / yesWeightsSum) * (noPot - NO_SEED)
-    const noPayout = noBid + (noWeight / noWeightsSum) * (yesPot - YES_SEED)
     const yesReturn = (yesPayout - yesBid) / yesBid
     const noReturn = (noPayout - noBid) / noBid
     entries.push({ ...weight, yesPayout, noPayout, yesReturn, noReturn })

web/lib/util/format.ts

@@ -6,11 +6,11 @@ const formatter = new Intl.NumberFormat('en-US', {
 })
 
 export function formatMoney(amount: number) {
-  return 'M$ ' + formatter.format(amount).substring(1)
+  return 'M$ ' + formatter.format(amount).replace('$', '')
 }
 
 export function formatWithCommas(amount: number) {
-  return formatter.format(amount).substring(1)
+  return formatter.format(amount).replace('$', '')
 }
 
 export function formatPercent(zeroToOne: number) {

web/pages/[username]/[contractSlug].tsx

@@ -97,7 +97,7 @@ function BetsSection(props: { contract: Contract; user: User | null }) {
 
   return (
     <div>
-      <Title text="Your bets" />
+      <Title text="Your trades" />
       <MyBetsSummary contract={contract} bets={userBets} />
       <Spacer h={6} />
       <ContractBetsTable contract={contract} bets={userBets} />

web/pages/about.tsx

@@ -162,8 +162,8 @@ function Contents() {
       </p>
       <h3 id="how-are-markets-resolved-">How are markets resolved?</h3>
       <p>
-        The creator of the prediction market decides the outcome and earns 0.5%
+        The creator of the prediction market decides the outcome and earns 1% of
-        of the trade volume for their effort.
+        the betting pool for their effort.
       </p>
       <p>
         This simple resolution mechanism has surprising benefits in allowing a

web/pages/simulator.tsx

@@ -86,7 +86,7 @@ function TableRowEnd(props: { entry: Entry | null; isNew?: boolean }) {
     return (
       <>
         <td>{(entry.prob * 100).toFixed(1)}%</td>
-        <td>${(entry.yesBid + entry.yesWeight).toFixed(0)}</td>
+        <td>${entry.yesWeight.toFixed(0)}</td>
         {!props.isNew && (
           <>
             <td>${entry.yesPayout.toFixed(0)}</td>
@@ -99,7 +99,7 @@ function TableRowEnd(props: { entry: Entry | null; isNew?: boolean }) {
     return (
       <>
         <td>{(entry.prob * 100).toFixed(1)}%</td>
-        <td>${(entry.noBid + entry.noWeight).toFixed(0)}</td>
+        <td>${entry.noWeight.toFixed(0)}</td>
         {!props.isNew && (
           <>
             <td>${entry.noPayout.toFixed(0)}</td>
@@ -149,9 +149,9 @@ function NewBidTable(props: {
 
   function randomBid() {
     const bidType = Math.random() < 0.5 ? 'YES' : 'NO'
-    const p = bidType === 'YES' ? nextEntry.prob : 1 - nextEntry.prob
+    // const p = bidType === 'YES' ? nextEntry.prob : 1 - nextEntry.prob
 
-    const amount = Math.round(p * Math.random() * 300) + 1
+    const amount = Math.floor(Math.random() * 300) + 1
     const bid = makeBid(bidType, amount)
 
     bids.splice(steps, 0, bid)
@@ -238,7 +238,7 @@ function NewBidTable(props: {
 // Show a hello world React page
 export default function Simulator() {
   const [steps, setSteps] = useState(1)
-  const [bids, setBids] = useState([{ yesBid: 550, noBid: 450 }])
+  const [bids, setBids] = useState([{ yesBid: 100, noBid: 100 }])
 
   const entries = useMemo(
     () => makeEntries(bids.slice(0, steps)),

web/pages/trades.tsx

@@ -4,13 +4,13 @@ import { SEO } from '../components/SEO'
 import { Title } from '../components/title'
 import { useUser } from '../hooks/use-user'
 
-export default function BetsPage() {
+export default function TradesPage() {
   const user = useUser()
 
   return (
     <Page>
-      <SEO title="Your bets" description="Your bets" url="/bets" />
+      <SEO title="Your trades" description="Your trades" url="/trades" />
-      <Title text="Your bets" />
+      <Title text="Your trades" />
       {user && <BetsList user={user} />}
     </Page>
   )