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Market Foundations & Exchange Microstructure

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Lesson 11/12/Market Foundations/Indian Markets & SEBI/Regulation & Costs13 min

Transaction Costs, STT, Exchange Fees & Net Breakeven Math

Market Foundations

Exact statutory cost formulas for Indian Equity, Futures, and Options—and why ITM expiry exercise must be avoided.

Key Topics & Tags
sttstamp dutygsttransaction chargesbreakevenitm exercise

Core Architecture & Intuition

In Indian markets, brokerage is only the tip of the cost iceberg. Every trade pays Securities Transaction Tax (STT), NSE/BSE Exchange Turnover Charges, SEBI regulatory fees, Stamp Duty, and 18% GST on service components.

Furthermore, allowing a bought In-The-Money (ITM) option to expire un-squared at 3:30 PM can trigger intrinsic settlement charges or physical stock delivery obligations. Always square off long ITM options in the open market before 3:25 PM.

Hover over key terms below for instant definitions: Securities Transaction Tax (STT), Net Breakeven Points, and Physical Delivery Margin. For the complete mathematical derivation and edge-case analysis, open .

Half-Kelly (Optimal Live Sizing)1.0x Full Kelly PeakOver-Leverage RegimeHigher variance · Lower geometric growthPosition Risk Fraction (f%) vs. Long-Run Geometric Compounding Growth Rate (G)
Round-trip statutory friction and net breakeven point threshold per lot.
!
Caution:Never leave a long ITM option to auto-expire at 3:30 PM—always square it off in the market before 3:25 PM.

Interactive Concept Breakdown

  • Securities Transaction Tax (STT) — Directly scales with turnover regardless of trade profitability.
  • Net Breakeven Points — Minimum points the contract must move in your favor just to break even after all costs.
  • Physical Delivery Margin — Individual stock F&O contracts settle physically—close or roll before expiry week.

Step-by-Step Execution Protocol: Regulation & Costs

  1. 1
    Compute Buy & Sell Turnover
    Multiply premium (for options) or contract price (for futures) by total quantity.
  2. 2
    Sum All 5 Statutory Components
    Add Brokerage + STT + Exchange Turnover Charge + SEBI Fee + Stamp Duty + 18% GST.
  3. 3
    Divide by Lot Size for Breakeven Points
    Verify your strategy's average winner is at least 4x your round-trip breakeven cost.

Parameters, Rules & Reference Matrix

Parameter / RuleTypeDefaultDescription
gstRate%18%Applied on Brokerage + Exchange + SEBI fees.
minEdgeToFrictionRatioratio>= 4.0xGross expectancy should exceed 4x total transaction friction.

Implementation & Quantitative Model

fno-charges.ts
export function calcOptionCharges(buyPrem: number, sellPrem: number, qty: number, brok = 40) {  const buyTurn = buyPrem * qty;  const sellTurn = sellPrem * qty;  const stt = sellTurn * 0.001;  const exch = (buyTurn + sellTurn) * 0.0003503;  const stamp = buyTurn * 0.00003;  const gst = 0.18 * (brok + exch);  const total = brok + stt + exch + stamp + gst;  return { totalCharges: Number(total.toFixed(2)), breakevenPts: Number((total / qty).toFixed(2)) };}

Desk Verification Checklist

Confirm before deploying live capital

  • Deduct realistic statutory taxes and brokerage in every backtest.
  • Square off long ITM index options before 3:25 PM on expiry days.
  • Close or roll individual stock options 4 days before monthly expiry.

Cross-reference standard risk definitions such as drawdown, slippage, and when auditing your logs.

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