Pricing & Calculation

Browse available strikes, calculate exact loan costs, and check promotional pricing eligibility.

Fetch Strike Options

getStrikeOptions() fetches live pricing from the Deribit-style API, filters for valid OTM put options, calculates estimated APRs, and groups results by expiry date.

import { ThetanutsClient } from '@thetanuts-finance/thetanuts-client';

const client = new ThetanutsClient({ chainId: 8453, provider });

// ETH strikes with default settings
const groups = await client.loan.getStrikeOptions('ETH');

// BTC strikes with custom filters
const btcGroups = await client.loan.getStrikeOptions('BTC', {
  minDurationDays: 30,   // At least 30 days to expiry
  maxStrikes: 5,         // Top 5 strikes per expiry
  sortOrder: 'highestStrike',
  maxApr: 15,            // Borrowing rate for cost estimation
});

Strike Settings

Setting	Default	Description
minDurationDays	7	Minimum days until expiry
maxStrikes	20	Maximum strikes per expiry group
sortOrder	'highestStrike'	'highestStrike', 'lowestStrike', 'nearestExpiry', 'furthestExpiry'
maxApr	20	Borrowing APR used for cost estimation (not a filter)

Strike Option Fields

Each option in a group contains:

Field	Type	Description
strike	number	Strike price in USD
strikeFormatted	string	"$1,600"
expiry	number	Unix timestamp
expiryFormatted	string	"Fri, March 28, 2025"
expiryLabel	string	Deribit format: "28MAR25"
underlyingPrice	number	Current underlying price
askPrice	number	Option ask price (fraction of underlying)
impliedLoanAmount	number	Estimated receive per unit of collateral
effectiveApr	number	All-in APR including all costs
isPromo	boolean	Promotional pricing eligible

---

Calculate Loan Costs

calculateLoan() is synchronous — pure BigInt math, no network calls. Use it after selecting a strike from getStrikeOptions().

const calc = client.loan.calculateLoan({
  depositAmount: '2.5',       // 2.5 ETH
  underlying: 'ETH',
  strike: 1800,               // $1,800 strike
  expiryTimestamp: 1780041600, // Unix seconds
  askPrice: 0.007,             // from strike option
  underlyingPrice: 2500,       // from strike option
  maxApr: 20,                  // borrowing rate (default: 20)
});

if (calc) {
  // Raw BigInt values (USDC, 6 decimals)
  console.log(calc.owe);             // Total owed at expiry
  console.log(calc.optionCost);      // Option premium
  console.log(calc.capitalCost);     // Borrowing fee
  console.log(calc.protocolFee);     // Protocol fee (4 bps)
  console.log(calc.totalCosts);      // Sum of all costs
  console.log(calc.finalLoanAmount); // What you receive

  // Formatted strings
  console.log(calc.formatted.receive);    // "4198.23"
  console.log(calc.formatted.repay);      // "4500.00"
  console.log(calc.formatted.optionCost); // "43.7500"
  console.log(calc.formatted.capitalCost);// "98.6301"
  console.log(calc.formatted.protocolFee);// "1.8000"
  console.log(calc.formatted.apr);        // "14.52"

  // Use finalLoanAmount as minSettlementAmount in requestLoan()
  await client.loan.requestLoan({
    underlying: 'ETH',
    collateralAmount: '2.5',
    strike: 1800,
    expiryTimestamp: 1780041600,
    minSettlementAmount: calc.finalLoanAmount,
  });
}

Returns null if inputs are invalid (zero deposit, zero strike, etc.) or if the final loan amount would be negative.

---

Promotional Pricing

Check if a specific strike qualifies for promotional rates:

const isPromo = client.loan.isPromoOption(
  1200,           // strike price in USD
  2500,           // current underlying price
  1790041600,     // expiry timestamp
  50000,          // estimated loan amount in USD (optional, for $250k cap)
);

console.log(isPromo); // true if eligible

Promo Eligibility Rules

Condition	Requirement
Days to expiry	> 90 days
LTV ratio	< 50% (strike / underlyingPrice)
Loan amount	< $250,000 per person
Total pool	< $2,000,000 across all promo loans

When promo applies:

• Option premium is waived (optionCost = 0)

• Borrowing APR is fixed at 5.68%

---

Raw Pricing Data

Access the underlying Deribit-style pricing API directly:

const pricing = await client.loan.fetchPricing();

// pricing['ETH']['ETH-28MAR25-3000-P'] = {
//   underlying_price: 2500,
//   ask_price: 0.007,
//   mark_price: 0.0065,
// }

// Cached for 30 seconds — subsequent calls return cached data
const cached = await client.loan.fetchPricing(); // instant if < 30s

---

See Also

• Overview — Module overview and cost formula

• Borrowing — Full borrowing workflow

• Lending — Fill limit orders and earn yield