Master order execution mechanics

4.3.1 · Stock-Market › How to Trade — Execution & Platforms

Core Concept

Order execution mechanics woh process hai jiske through aapka buy/sell instruction aapki screen se exchange tak travel karta hai aur ek counterparty se match hota hai. Isko samajhna decide karta hai ki aapko aapki desired price par fill milegi ya nahi, aap kitna slippage pay karenge, aur aapka order kabhi kabhi unfilled kyun rehta hai.

Ek buri tarah execute hui trade aapko ek volatile stock par 0.5-2% slippage mein cost kar sakti hai. ₹1,00,000 ki trade par, yeh sirf execution mein ₹500-₹2000 ka loss hai—aapki ₹20 brokerage fee se kaafi zyada.

The Order Execution Journey

Step 1: Order Placement (Client → Broker)

Aap apne broker ke platform (web/app) ke through ek order submit karte ho. Order mein hota hai:

YEH kyun matter karte hain: Har parameter change karta hai ki aapki order kaise aur kab fill hogi. Ek market order price ke upar speed ko priority deta hai; ek limit order speed ke upar price ko priority deta hai.

Step 2: Broker Validation & Risk Checks

Exchange par bhejne se pehle, broker:

1. Margins check karta hai: Kya aapke paas sufficient funds/stocks hain?
   • Kyun: Naked short selling ya unpaid purchases (settlement failures) rokne ke liye
2. Order params validate karta hai: Kya price circuit limits ke andar hai? Quantity lot sizes mein hai?
3. Risk management: Unusually large orders ya suspected manipulation ko flag karta hai

Agar validation pass ho jaaye, toh broker ek order ID assign karta hai aur usse aage bhejta hai.

Step 3: Order Routing (Broker → Exchange)

Indian brokers orders route karte hain:

• NSE (National Stock Exchange)
• BSE (Bombay Stock Exchange)
• Kabhi kabhi dono par, aapki selection aur liquidity ke hisaab se

Do routing models:

Routing kyun matter karta hai: NSE mein RELIANCE ke liye tighter spreads ho sakte hain, lekin BSE mein kisi mid-cap ke liye better depth mil sakti hai. Smart order routing (SOR) systems aapki order ko slippage minimize karne ke liye exchanges mein split kar dete hain.

Step 4: Order Book Matching (Exchange)

Exchange ek order book maintain karta hai—sabhi buy aur sell orders ki ek live list, price aur time ke hisaab se sorted.

Yeh kaise kaam karta hai:

BUY side (bids) descending sorted: | Price | Quantity | Time | |-------|----------| | ₹150.50 | 100 | 10:00:01 | | ₹150.50 | 200 | 10:00:03 | | ₹150.00 | 500 | 10:00:00 |

SELL side (asks) ascending sorted:

Matching rules:

1. Ek market buy lowest ask se match karta hai (₹151.00)
2. Ek limit buy at ₹151 abhi match NAHI karega (best ask ₹151 hai, kisi ko ≤₹151 par bechne ke liye willing hona chahiye)
3. Agar aap limit buy at ₹151.50 place karo, toh aap ₹151.00 ask ke saath turant match karoge (aapko aapke limit se better price milti hai)

Order book state:

• Best ask: ₹151.00 (300 available)
• Next ask: ₹151.50 (150 available)
• Next ask: ₹152.00 (400 available)

Execution:

1. Pehle 300 shares: ₹151.00 par fill (₹45,300)
2. Agle 150 shares: ₹151.50 par fill (₹22,725)
3. Aakhiri 50 shares: ₹152.00 par fill (₹7,600)

Total cost: ₹75,625 → Average price = ₹151.25

Yeh kyun matter karta hai: Aapki "market" order order book mein upar chal gayi. Weighted average price (WAP) best ask se zyada hai. Yahi slippage hai.

Is example mein:

₹75,625 ki trade par, slippage = ₹125. ₹10,000 ki trade par, yeh scale hokar ₹1,650 banta hai.

Step 5: Trade Confirmation & Settlement

Match hone ke baad:

1. Trade confirmation: Buyer aur seller dono ko fill notification milti hai jisme hota hai:

   • Execution price(s)
   • Quantity filled
   • Trade time (millisecond tak)
   • Unique trade ID

2. Clearing: Exchange ki clearing corporation (NSE ke liye NSCCL) dono sides ka counterparty ban jaati hai, settlement guarantee karte hue.

3. Settlement cycle: India mein T+1 (Trade date + 1 working day)

   • Aap Monday ko kharidein → Shares Tuesday ko aapke demat mein credit
   • Aap Monday ko bechein → Funds Tuesday ko credit

T+1 kyun: Banking system aur demat network (NSDL/CDSL) ke through funds aur securities move karne ka time deta hai.

Order Types Deep Dive

1. Market Order

Advantages:

• Guaranteed execution (agar liquidity ho)
• Instant fills

Disadvantages:

• Koi price protection nahi: Fast-moving market mein aapko bahut buri price mil sakti hai
• Large orders ya illiquid stocks par high slippage

Momentary liquidity vacuum ki wajah se aapne expected se 5% zyada pay kiya.

Kab use karein: High liquidity stocks (Nifty 50), chhoti orders, jab execution certainty kuch paise se zyada matter kare.

2. Limit Order

Advantages:

• Price protection
• Aapke limit se zyada slippage nahi

Disadvantages:

• Kabhi execute na ho agar market aapki price tak na pahunche
• Partial fills (kuch quantity execute, baaki cancel)

Setup: ₹490 par 100 shares ke liye limit buy place karo.

Scenario A: Stock ₹489.50 touch karta hai → Aapki order ₹490 par fill hoti hai (aapko aapke limit se better price milti hai).

Scenario B: Stock ₹491 tak girta hai aur rebound karta hai → Aapki order saara din unfilled rehti hai. Aap trade miss karte ho.

Kab use karein: Jab aapke paas ek target entry/exit price ho aur aap trade miss karne ke liye willing ho agar market cooperate na kare.

3. Stop-Loss Order (SL / SL-M)

Structure:

• Trigger price: ₹95 (kab activate karna hai)
• Limit price: ₹94 (SL-Limit ke liye worst acceptable execution)

Yeh kaise kaam karta hai:

Aapne ek stock ₹100 par kharida. Losses limit karne ke liye, aap trigger ₹95 par SL-M sell place karte ho.

• Stock ₹97, ₹96 tak girta hai... order dormant rehti hai
• Stock ₹95 touch karta hai → Order market sell mein convert ho jaati hai
• Best available bid par execute hoti hai (girte market mein ₹94.80 ho sakta hai)

Trigger ≠ execution price kyun: Trigger aur execution ke beech, market move karta rehta hai. Crash mein, gap down bhi ho sakta hai.

SL-Market (SL-M):

• Stock crash karta hai, ₹95 par trigger hoti hai
• ₹94.50 par execute hoti hai (best available)
• Result: Aap exit karte ho, 5.5% loss lete hue

SL-Limit (trigger ₹95, limit ₹94):

• Stock crash karta hai, ₹95 par trigger hoti hai
• Order book mein "₹94 ya better par becho" ke roop mein baith jaati hai
• Agar market ₹92 tak gap down kare, aapki order execute nahi hoti (aapko ≥₹94 chahiye tha)
• Stock ₹88 tak girta hai aapke react karne se pehle
• Result: 12% loss kyunki aapne execution par price ko priority di

Kab kaunsa use karein:

• SL-M: Jab aapko zaroor exit karna ho (risk management price se zyada important hai)
• SL-Limit: Jab aap ridiculous buri prices par panic selling se bachna chahte ho (non-execution ka risk accept karte hue)

4. After Market Order (AMO)

Timing: 3:45 PM se 8:57 AM (agle din) tak accepted.

AMOs kaise execute hote hain:

• Orders pre-open session (9:00-9:08 AM) mein enter karte hain
• Exchange ek equilibrium price calculate karta hai jo traded volume maximize kare
• Sabhi AMOs is single opening price par execute hote hain

Action: Apni holdings market price par bechne ke liye AMO place karo.

Agle din:

• Pre-open equilibrium: ₹480 (stock ₹500 par close hua tha)
• Aapka AMO ₹480 par execute hota hai
• Regular session open hota hai, stock ₹470 tak girta hai
• Aapne regular hours ka wait karne ki jagah AMO use karke ₹10/share bachaye

Risks: Agar aapne galat judge kiya aur markets upar gap karein, toh aapki sell closing se zyada price par execute hoti hai (aur gains miss karne ka opportunity cost).

Order Validity Types

Day Order

3:30 PM tak active rehti hai, phir unfilled hone par auto-cancel ho jaati hai.

Immediate or Cancel (IOC)

Turant execute honi chahiye (fully ya partially). Koi bhi unfilled quantity instantly cancel ho jaati hai.

Use case: Order book mein order chhode bina liquidity test karna.

Good Till Cancelled (GTC)

NSE/BSE par equities ke liye available nahi. US markets mein common hai (order 30-90 din tak active rehti hai).

Execution Quality Ko Affect Karne Wale Factors

1. Liquidity

Spread ka formula:

Stock B (Low liquidity): Best bid ₹50.00, best ask ₹52.00

₹1,00,000 ki trade par, Stock B ka spread akela aapko slippage mein ₹3,920 cost karta hai.

2. Order Size vs. Depth

First principles se derivation:

Maano $Q$ = aapki order size, $D_i$ = price level $i$ par depth.

Agar $Q>D_1$ (aapki order best price depth se zyada hai), aap "book walk" karte ho:

Iska matlab: Aapki order ka har "slice" agle price level mein jaata hai. Badi orders = guaranteed slippage.

Aap 100 shares kharidein:

• 50 @ ₹100.00 = ₹5,000
• 50 @ ₹100.10 = ₹5,005
• Avg price: ₹100.05

Aap 250 shares kharidein:

• 50 @ ₹100.00 = ₹5,000
• 100 @ ₹100.10 = ₹10,010
• 100 @ ₹100.25 = ₹10,025
• Avg price: ₹100.14

Badi order → buri price, chahe aapne ek single instruction submit ki ho.

3. Volatility & Timing

Volatility slippage badhata hai kyunki:

• Order book thin ho jaata hai (uncertain conditions mein traders orders pull kar lete hain)
• Spreads widen ho jaate hain
• Prices aapke order submission aur execution ke beech jump karte hain (milliseconds bhi matter karte hain)

Trade karne ke worst times (highest slippage):

1. Pehle 15 minute (9:15-9:30 AM): Opening volatility, amateur traders, order imbalances
2. Aakhiri 15 minute (3:15-3:30 PM): Institutional squaring off, fund managers positions close karte hue
3. News events: Earnings, policy announcements, global shocks

Best times: 10:00 AM - 2:30 PM (mid-session, stable liquidity).

Common Execution Mistakes

Steel-man: Momentum breakout mein, aapki limit price ka wait karna matlab ho sakta hai poora move miss karna. FOMO ek powerful force hai.

Kyun galat hai: 5% spreads wali stock par, aapki market order guarantee karti hai trade start hone se pehle 2-3% ka loss. Aap bet kar rahe ho ki stock execution costs break even karne ke liye >5% move kare.

Fix:

• Best ask ke paas limit orders use karo (buys ke liye) / best bid ke paas (sells ke liye)
• Agar 30 seconds mein fill nahi hoti, re-evaluate karo ki kya aap sach mein yeh illiquid stock chahte ho
• Socho: Agar koi trade karne wala nahi hai, baad mein aap kisko bechoge?

Steel-man: Risk management books kehti hain "ek trade mein 1-2% se zyada mat gawao." Tight stops disciplined lagte hain.

Kyun galat hai: Stocks mein normal intraday volatility hoti hai. 2% stop wali stock jo routinely intraday ±3% swing karti hai matlab hai aap noise se stop out ho jaoge, trade galat hone se nahi.

Fix:

1. Stock ka Average True Range (ATR) measure karo

jahan $H$ = high, $L$ = low, $C$ = close.

2. Stops 1.5× se 2× ATR entry se place karo

   • Agar ATR = ₹5, aur aap ₹100 par enter karo, ₹90-₹92.50 par stop use karo

3. Position size adjust karo taaki yeh wider stop phir bhi aapka rupee loss tolerance ke andar rakhe:

Stock: BHEL ₹100 par, ATR = ₹4.

Stop distance: 2× ATR = ₹8 → Stop ₹92 par.

Position size:

Capital required: 125 × ₹100 = ₹12,500.

Ab agar trade fail ho, aap exactly ₹1,000 (1%) lose karte ho, lekin aapne trade ko breathe karne ki room di.

Kyun galat hai: Backtests assume karte hain aap close price ya open price par execute karte ho. Reality:

• Market orders mein 0.1-0.5% slippage hoti hai
• Intraday scalping strategies backtest mein 50%+ returns dikhati hain lekin live mein slippage ki wajah se paise lose karti hain

Fix: Apne backtest mein realistic execution costs add karo:

# Example: Adjusting backtest for slippage
entry_price = data['close'] * 1.001  # 0.1% slippage on entry
exit_price = data['close'] * 0.999   # 0.1% slippage on exit

Agar aapki strategy 0.2-0.5% round-trip costs ke saath bhi kaam karti hai, toh yeh shayad real trading mein survive kare.

Platform-Specific Execution Features

Bracket Orders (BO)

Ek 3-in-1 order:

1. Entry (limit ya market)
2. Target (limit sell/buy)
3. Stop-loss (SL-M)

Entry execute hone ke baad, target aur stop-loss dono auto-place ho jaate hain. Agar ek execute ho, doosra auto-cancel ho jaata hai.

Use case: Intraday trading jahan aap "set and forget" apna risk/reward karna chahte ho.

Constraint: BO delivery trades ke liye allowed nahi (sirf MIS).

Cover Orders (CO)

Entry + compulsory stop-loss ek single instruction mein. Aap stop-loss ke bina position nahi rakh sakte.

Advantage: Kam margin requirements (kyunki risk stop se capped hai).

Risk: Agar markets aapke stop ke through gap karein, aap stop level se zyada losses face karte ho.

Iceberg Orders

Institutions use karte hain. Ek badi order place karta hai lekin order book mein sirf ek chhoti "visible" quantity dikhata hai.

Example: Aap 10,000 shares kharidna chahte ho lekin ek time par sirf 500 show karte ho. Jaise 500 fill hote hain, agle 500 appear hote hain.

Kyun: Doosre traders ko tip off karne se bachata hai ki market mein ek bada buyer hai (jo prices drive up kar dega).

Execution Quality Monitor Karna

Track Karne Wale Metrics

1. Realized Slippage:

2. Fill Rate: Limit orders ka percentage jo execute hoti hain

   • <50% → Aap aise prices chase kar rahe ho jo kabhi aate hi nahi

   • 90% → Aap shayad overpay kar rahe ho (bahut aggressive limits)

3. Average Execution Time: Market orders ke liye, liquid stocks mein <1 second hona chahiye

4. Partial Fill Frequency: High rate suggest karta hai aapki order size ke liye insufficient liquidity

Market order: Aap chillate ho "Main tamatar jo bhi price ho khareed lunga!" Seller yeh sun ke zyada charge karta hai kyunki aap desperate ho. Aapko turant tamatar milte hain, lekin zyada pay karte ho.

Limit order: Aap kehte ho "Main sirf ₹40 per kg dunga." Ab wait karna padega. Agar koi seller agree kare, great. Agar nahi, toh aap bina tamatar ke ghar jaate ho.

Stop-loss: Aapne pehle se ₹40 par tamatar kharida. Aap apne dost ko bolo, "Agar price ₹30 tak gire, mera tamatar turant becho." Is tarah, agar tamatar sadne lage (value khone lage), aap bahut zyada kho ne se pehle bahar nikal jaate ho.

Order book ek badi board jaisi hoti hai jo dikhati hai:

• Log tamatar KHARIDNE ko taiyar hain aur kis price par (sabse zyada price upar)
• Log tamatar BECHNE ko taiyar hain aur kis price par (sabse kam price upar)

Jab buyer ki price seller ki price se match hoti hai, trade hota hai! Sabzi mandi ka uncle (exchange) ensure karta hai ki dono sides rules follow karein.

Agar aap 100 kg tamatar kharidne ki koshish karo lekin ₹40 par sirf 20 kg hain, toh agle batch ke liye ₹42 pay karna padega, aur uske agle ke liye ₹45. Yahi slippage hai—jitna zyada kharidoge, utna zyada pay karoge.

Connections

• Order book dynamics and depth analysis — Short-term moves predict karne ke liye order book kaise padhein
• Bid-ask spread and market liquidity — Spreads kyun matter karte hain aur liquidity kaise measure karein
• Brokerage models and fee structures — Brokers aapki orders se paise kaise kamaate hain (PFOF, ST, etc.)
• Risk management and position sizing — Sahi position sizes calculate karne ke liye execution mechanics use karna
• Market microstructure and price discovery — Micro level par trades kaise prices determine karte hain
• Algorithmic trading and smart order routing — Institutions algos se slippage kaise minimize karti hain
• Pre-open and post-close sessions — Alag rules wale special trading sessions
• Circuit breakers and trading halts — Exchange order execution kab aur kyun freeze karta hai

#flashcards/stock-market

Market order aur limit order mein kya difference hai? :: Market order best available price par immediately execute hoti hai (koi price control nahi, guaranteed execution). Limit order sirf aapki specified price ya better par execute hoti hai (price control, fill na ho paye).

Concept Map