diff --git a/frontend/src/app/contracts/ContractBorrowerOperations.tsx b/frontend/src/app/contracts/ContractBorrowerOperations.tsx
index 68ef7058..841b0cd6 100644
--- a/frontend/src/app/contracts/ContractBorrowerOperations.tsx
+++ b/frontend/src/app/contracts/ContractBorrowerOperations.tsx
@@ -1,12 +1,11 @@
-import type { Address } from "@/src/types";
 import type { Dnum } from "dnum";
 
 import { BorrowerOperations } from "@/src/abi/BorrowerOperations";
 import { FormField } from "@/src/comps/FormField/FormField";
 import { TextInput } from "@/src/comps/Input/TextInput";
 import { CONTRACT_BORROWER_OPERATIONS } from "@/src/env";
-import { ADDRESS_ZERO } from "@/src/eth-utils";
-import { parseInputAddress, parseInputPercentage, parseInputValue } from "@/src/form-utils";
+import { parseInputInt, parseInputPercentage, parseInputValue } from "@/src/form-utils";
+import { getTroveId } from "@/src/liquity-utils";
 import * as dn from "dnum";
 import { useState } from "react";
 import { useAccount, useWriteContract } from "wagmi";
@@ -28,33 +27,38 @@ export function ContractBorrowerOperations() {
   );
 }
 
+type FormValue<T> = [fieldValue: string, parsedValue: T];
+
 function OpenTrove() {
   const account = useAccount();
   const { writeContract } = useWriteContract();
 
   const [formValues, setFormValues] = useState<{
-    maxFeePercentage: [string, Dnum];
-    boldAmount: [string, Dnum];
-    upperHint: [string, Address];
-    lowerHint: [string, Address];
-    annualInterestRate: [string, Dnum];
-    ethValue: [string, Dnum];
+    ownerIndex: FormValue<bigint>;
+    maxFeePercentage: FormValue<Dnum>;
+    boldAmount: FormValue<Dnum>;
+    upperHint: FormValue<Dnum>;
+    lowerHint: FormValue<Dnum>;
+    annualInterestRate: FormValue<Dnum>;
+    ethAmount: FormValue<Dnum>;
   }>(() => ({
+    ownerIndex: ["", 0n],
     maxFeePercentage: ["", dn.from(0, 18)],
     boldAmount: ["", dn.from(0, 18)],
-    upperHint: ["", ADDRESS_ZERO],
-    lowerHint: ["", ADDRESS_ZERO],
+    upperHint: ["", dn.from(0, 18)],
+    lowerHint: ["", dn.from(0, 18)],
     annualInterestRate: ["", dn.from(0, 18)],
-    ethValue: ["", dn.from(0, 18)],
+    ethAmount: ["", dn.from(0, 18)],
   }));
 
   const formProps = Object.fromEntries([
+    ["ownerIndex", parseInputInt] as const,
     ["maxFeePercentage", parseInputValue] as const,
     ["boldAmount", parseInputValue] as const,
-    ["upperHint", parseInputAddress] as const,
-    ["lowerHint", parseInputAddress] as const,
+    ["upperHint", parseInputValue] as const,
+    ["lowerHint", parseInputValue] as const,
     ["annualInterestRate", parseInputPercentage] as const,
-    ["ethValue", parseInputValue] as const,
+    ["ethAmount", parseInputValue] as const,
   ].map(([name, valueParser]) => [name, {
     onChange: (value: string) => {
       const parsedValue = valueParser(value);
@@ -75,26 +79,28 @@ function OpenTrove() {
         address: CONTRACT_BORROWER_OPERATIONS,
         functionName: "openTrove",
         args: [
+          account.address,
+          formValues.ownerIndex[1],
           formValues.maxFeePercentage[1][0],
+          formValues.ethAmount[1][0],
           formValues.boldAmount[1][0],
-          formValues.upperHint[1],
-          formValues.lowerHint[1],
+          formValues.upperHint[1][0],
+          formValues.lowerHint[1][0],
           formValues.annualInterestRate[1][0],
         ],
-        value: formValues.ethValue[1][0],
       });
     }
   };
 
   const onFillExample = () => {
-    const address = account.address ?? ADDRESS_ZERO;
     setFormValues({
+      ownerIndex: ["0", 0n],
       maxFeePercentage: ["100", [100n * 10n ** 16n, 18]],
       boldAmount: ["1800", [1800n * 10n ** 18n, 18]],
-      upperHint: [address, address],
-      lowerHint: [address, address],
+      upperHint: ["0", [0n, 18]],
+      lowerHint: ["0", [0n, 18]],
       annualInterestRate: ["5", [5n * 10n ** 16n, 18]],
-      ethValue: ["20", [20n * 10n ** 18n, 18]],
+      ethAmount: ["20", [20n * 10n ** 18n, 18]],
     });
   };
 
@@ -104,9 +110,15 @@ function OpenTrove() {
       onSubmit={onSubmit}
       title="Open Trove"
     >
+      <FormField label="Owner Index">
+        <TextInput {...formProps.ownerIndex} />
+      </FormField>
       <FormField label="Max Fee Percentage">
         <TextInput {...formProps.maxFeePercentage} />
       </FormField>
+      <FormField label="ETH Amount">
+        <TextInput {...formProps.ethAmount} />
+      </FormField>
       <FormField label="BOLD Amount">
         <TextInput {...formProps.boldAmount} />
       </FormField>
@@ -119,9 +131,6 @@ function OpenTrove() {
       <FormField label="Annual Interest Rate">
         <TextInput {...formProps.annualInterestRate} />
       </FormField>
-      <FormField label="Collateral (value)">
-        <TextInput {...formProps.ethValue} />
-      </FormField>
     </ContractAction>
   );
 }
@@ -129,20 +138,50 @@ function OpenTrove() {
 function CloseTrove() {
   const account = useAccount();
   const { writeContract } = useWriteContract();
+
+  const [formValues, setFormValues] = useState<{
+    ownerIndex: FormValue<bigint>;
+  }>(() => ({
+    ownerIndex: ["", 0n],
+  }));
+
+  const formProps = Object.fromEntries([
+    ["ownerIndex", parseInputInt] as const,
+  ].map(([name, valueParser]) => [name, {
+    onChange: (value: string) => {
+      const parsedValue = valueParser(value);
+      if (parsedValue !== null) {
+        setFormValues((values) => ({
+          ...values,
+          [name]: [value, parsedValue],
+        }));
+      }
+    },
+    value: formValues[name][0],
+  }]));
+
+  const onSubmit = () => {
+    if (account.address) {
+      writeContract({
+        abi: BorrowerOperations,
+        address: CONTRACT_BORROWER_OPERATIONS,
+        functionName: "closeTrove",
+        args: [
+          getTroveId(account.address, formValues.ownerIndex[1]),
+        ],
+      });
+    }
+  };
+
   return (
     <ContractAction
       title="Close Trove"
-      onSubmit={() => {
-        if (account.address) {
-          writeContract({
-            abi: BorrowerOperations,
-            address: CONTRACT_BORROWER_OPERATIONS,
-            functionName: "closeTrove",
-            args: [],
-          });
-        }
-      }}
-    />
+      onSubmit={onSubmit}
+    >
+      <FormField label="Owner Index">
+        <TextInput {...formProps.ownerIndex} />
+      </FormField>
+    </ContractAction>
   );
 }
 
diff --git a/frontend/src/app/contracts/page.tsx b/frontend/src/app/contracts/page.tsx
index 6bc55c48..2d6bd2d3 100644
--- a/frontend/src/app/contracts/page.tsx
+++ b/frontend/src/app/contracts/page.tsx
@@ -4,6 +4,7 @@ import type { ReactNode } from "react";
 
 import { ADDRESS_ZERO, shortenAddress } from "@/src/eth-utils";
 import {
+  getTroveId,
   useBoldBalance,
   useCloseTrove,
   useLiquity2Info,
@@ -54,7 +55,7 @@ function AccountDetails() {
   const { address } = useAccount();
   const balance = useBalance({ address: address ?? ADDRESS_ZERO });
   const boldBalance = useBoldBalance(address ?? ADDRESS_ZERO);
-  const rewards = useRewards(address ?? ADDRESS_ZERO);
+  const rewards = useRewards(getTroveId(address ?? ADDRESS_ZERO, 0n));
   return (
     <Card
       title="Account"
@@ -75,7 +76,7 @@ function AccountDetails() {
         )
         .when(
           ({ address, data }) => address && data.some(({ status }) => status === "error"),
-          () => <div>error</div>,
+          ({ data }) => <div>error</div>,
         )
         .with(
           {
@@ -122,21 +123,22 @@ function AccountDetails() {
 
 function TroveDetails() {
   const { address } = useAccount();
-  const troveDetails = useTroveDetails(address ?? ADDRESS_ZERO);
+  const troveDetails = useTroveDetails(address && getTroveId(address, 0n));
 
-  const closeTrove = useCloseTrove(address ?? ADDRESS_ZERO);
+  const closeTrove = useCloseTrove(getTroveId(address ?? ADDRESS_ZERO, 0n));
   const openTrove = useOpenTrove(address ?? ADDRESS_ZERO, {
+    ownerIndex: 0n,
     maxFeePercentage: 100n * 10n ** 16n, // 100%
     boldAmount: 1800n * 10n ** 18n, // 1800 BOLD
-    upperHint: address ?? ADDRESS_ZERO,
-    lowerHint: address ?? ADDRESS_ZERO,
+    upperHint: 0n,
+    lowerHint: 0n,
     interestRate: 5n * 10n ** 16n, // 5%
-    value: 20n * 10n ** 18n, // 20 ETH
+    ethAmount: 20n * 10n ** 18n, // 20 ETH
   });
 
   return (
     <Card
-      title="Trove"
+      title="Trove #0"
       action={match([troveDetails.data?.status, address])
         .with(
           [
@@ -193,7 +195,7 @@ function Liquity2Info() {
           <>
             <CardRow
               name="Troves Count"
-              value={data.trovesCount}
+              value="?"
             />
             <CardRow
               name="Total Collateral"
@@ -201,12 +203,12 @@ function Liquity2Info() {
             />
             <CardRow
               name="Total Debt"
-              value={dn.format(data.totalDebt) + " BOLD"}
+              value={dn.format(data.totalDebt, 2) + " BOLD"}
             />
             <CardRow
               name={
                 <>
-                  <abbr title="Total Collateral Ratio">TCR</abbr> ($4k/ETH)
+                  <abbr title="Total Collateral Ratio">TCR</abbr> ($200/ETH)
                 </>
               }
               value={dn.format(dn.mul(data.tcr, 100n), 2) + "%"}
@@ -326,13 +328,10 @@ function CardRow({
         alignItems: "center",
         gap: 80,
         height: 32,
+        whiteSpace: "nowrap",
       })}
     >
-      <div
-        className={css({
-          whiteSpace: "nowrap",
-        })}
-      >
+      <div>
         {name}
       </div>
       <div>{value}</div>
diff --git a/frontend/src/form-utils.ts b/frontend/src/form-utils.ts
index 6f9c1446..431c91b8 100644
--- a/frontend/src/form-utils.ts
+++ b/frontend/src/form-utils.ts
@@ -7,6 +7,12 @@ export function isInputValueFloat(value: string) {
   return inputValueRegex.test(value);
 }
 
+const inputIntRegex = /^[0-9]*$/;
+export function isInputValueInt(value: string) {
+  value = value.trim();
+  return inputIntRegex.test(value);
+}
+
 export function parseInputValue(value: string) {
   value = value.trim();
 
@@ -29,6 +35,11 @@ export function parseInputPercentage(value: string) {
   return dn.div(parsedValue, 100);
 }
 
+export function parseInputInt(value: string) {
+  value = value.trim();
+  return isInputValueInt(value) ? BigInt(value) : null;
+}
+
 export function parseInputAddress(value: string) {
   value = value.trim();
   return isAddress(value) ? value : ADDRESS_ZERO;
diff --git a/frontend/src/liquity-utils.ts b/frontend/src/liquity-utils.ts
index 2140e360..3e3d5e74 100644
--- a/frontend/src/liquity-utils.ts
+++ b/frontend/src/liquity-utils.ts
@@ -1,8 +1,9 @@
-import type { Address } from "@/src/types";
+import type { Address, TroveId } from "@/src/types";
 import type { Dnum } from "dnum";
 
 import { BoldTokenContract, BorrowerOperationsContract, TroveManagerContract } from "@/src/contracts";
 import { match } from "ts-pattern";
+import { encodeAbiParameters, keccak256, parseAbiParameters } from "viem";
 import { useReadContract, useReadContracts, useWriteContract } from "wagmi";
 
 type TroveStatus =
@@ -21,7 +22,7 @@ type TroveDetails = {
 };
 
 type LiquityInfo = {
-  trovesCount: number;
+  // trovesCount: number;
   totalCollateral: Dnum;
   totalDebt: Dnum;
   tcr: Dnum;
@@ -45,43 +46,40 @@ function troveStatusFromNumber(value: number): TroveStatus {
     });
 }
 
-export function useTroveDetails(borrower: Address) {
+export function useTroveDetails(troveId: TroveId = 0n) {
   const read = useReadContracts({
     allowFailure: false,
     contracts: [
       {
         ...TroveManagerContract,
         functionName: "getTroveStatus",
-        args: [borrower],
+        args: [troveId],
       },
       {
         ...TroveManagerContract,
         functionName: "getTroveStake",
-        args: [borrower],
+        args: [troveId],
       },
       {
         ...TroveManagerContract,
         functionName: "getTroveDebt",
-        args: [borrower],
+        args: [troveId],
       },
       {
         ...TroveManagerContract,
         functionName: "getTroveColl",
-        args: [borrower],
+        args: [troveId],
       },
       {
         ...TroveManagerContract,
         functionName: "getTroveAnnualInterestRate",
-        args: [borrower],
+        args: [troveId],
       },
     ],
   });
 
   if (!read.data || read.status !== "success") {
-    return {
-      ...read,
-      data: undefined,
-    };
+    return { ...read, data: undefined };
   }
 
   const troveStatusNumber = Number(read.data[0]);
@@ -94,26 +92,25 @@ export function useTroveDetails(borrower: Address) {
     interestRate: [read.data[4] ?? 0n, 18],
   };
 
-  return {
-    ...read,
-    data,
-  };
+  return { ...read, data };
 }
 
-export function useOpenTrove(address: Address, {
+export function useOpenTrove(owner: Address, {
+  ownerIndex,
   maxFeePercentage,
   boldAmount,
   upperHint,
   lowerHint,
   interestRate,
-  value,
+  ethAmount,
 }: {
+  ownerIndex: bigint;
   maxFeePercentage: bigint; // 0 to 1 * 10^18
   boldAmount: bigint; // amount * 10^18
-  upperHint: Address;
-  lowerHint: Address;
+  upperHint: bigint;
+  lowerHint: bigint;
   interestRate: bigint; // 0 to 1 * 10^18
-  value: bigint; // amount * 10^18
+  ethAmount: bigint; // amount * 10^18
 }) {
   const { writeContract } = useWriteContract();
   return () => (
@@ -121,26 +118,26 @@ export function useOpenTrove(address: Address, {
       ...BorrowerOperationsContract,
       functionName: "openTrove",
       args: [
+        owner,
+        ownerIndex,
         maxFeePercentage,
+        ethAmount,
         boldAmount,
         upperHint,
         lowerHint,
         interestRate,
       ],
-      account: address,
-      value: value,
     })
   );
 }
 
-export function useCloseTrove(address: Address) {
+export function useCloseTrove(troveId: TroveId) {
   const { writeContract } = useWriteContract();
   return () => (
     writeContract({
       ...BorrowerOperationsContract,
       functionName: "closeTrove",
-      args: [],
-      account: address,
+      args: [troveId],
     })
   );
 }
@@ -153,19 +150,19 @@ export function useBoldBalance(address: Address) {
   });
 }
 
-export function useRewards(address: Address) {
+export function useRewards(troveId: TroveId) {
   const read = useReadContracts({
     allowFailure: false,
     contracts: [
       {
         ...TroveManagerContract,
         functionName: "getPendingETHReward",
-        args: [address],
+        args: [troveId],
       },
       {
         ...TroveManagerContract,
         functionName: "getPendingBoldDebtReward",
-        args: [address],
+        args: [troveId],
       },
     ],
   });
@@ -192,11 +189,11 @@ export function useLiquity2Info() {
   const read = useReadContracts({
     allowFailure: false,
     contracts: [
-      {
-        ...TroveManagerContract,
-        functionName: "getTroveOwnersCount",
-        args: [],
-      },
+      // {
+      //   ...TroveManagerContract,
+      //   functionName: "getTroveOwnersCount",
+      //   args: [],
+      // },
       {
         ...TroveManagerContract,
         functionName: "getEntireSystemColl",
@@ -210,7 +207,7 @@ export function useLiquity2Info() {
       {
         ...TroveManagerContract,
         functionName: "getTCR",
-        args: [4_000n * 10n ** 18n],
+        args: [200n * 10n ** 18n],
       },
       {
         ...TroveManagerContract,
@@ -228,15 +225,19 @@ export function useLiquity2Info() {
   }
 
   const data: LiquityInfo = {
-    trovesCount: Number(read.data[0]),
-    totalCollateral: [read.data[1], 18],
-    totalDebt: [read.data[2], 18],
-    tcr: [read.data[3], 18],
-    redemptionRate: [read.data[4], 18],
+    // trovesCount: Number(read.data[0]),
+    totalCollateral: [read.data[0], 18],
+    totalDebt: [read.data[1], 18],
+    tcr: [read.data[2], 18],
+    redemptionRate: [read.data[3], 18],
   };
 
-  return {
-    ...read,
-    data,
-  };
+  return { ...read, data };
+}
+
+export function getTroveId(owner: Address, ownerIndex: bigint) {
+  return BigInt(keccak256(encodeAbiParameters(
+    parseAbiParameters("address, uint256"),
+    [owner, ownerIndex],
+  )));
 }
diff --git a/frontend/src/types.ts b/frontend/src/types.ts
index f64ddbb9..15bf5d6f 100644
--- a/frontend/src/types.ts
+++ b/frontend/src/types.ts
@@ -1 +1,3 @@
 export type Address = `0x${string}`;
+
+export type TroveId = bigint;