Learn about colocation and direct market access

6.5.4 · Stock-Market › HFT & Advanced Concepts

YEH DON CHEEZEIN HAIN KYA?

LATENCY KYU MATTER KARTI HAI — edge ko scratch se derive karo

Maan lo ek favourable price appear hoti hai. Do traders react karte hain. Jiska bhi order pehle matching engine tak pahunchta hai use good price par fill milti hai; haarne wale ko worse price milti hai ya kuch nahi.

Step 1 — total delay ko model karo. Round trip ko parts mein todo:

$T_{total} = t_{decide} + t_{propagation} + t_{broker} + t_{queue}$

Yeh step kyun? Har real delay inn buckets mein se kisi ek mein padni chahiye, isliye inhe sum karna honest total deta hai.

Step 2 — distance se propagation delay. Fiber mein signal speed: $v = \frac{c}{n} \approx \frac{3 \times 1 0 ^{8}}{1.5} = 2 \times 1 0^{8} m/s$

Kyun? Fiber ka refractive index $n \approx 1.5$ hota hai, isliye glass ke andar light vacuum se slower hoti hai. Phir distance $d$ par one-way time:

$t_{propagation} = \frac{d}{v}$

Step 3 — colocation gain dekho. Apna server $d_{1}$ (door) se $d_{2}$ (colocated) par move karne se bachta hai:

$Δ t = \frac{d _{1} - d _{2}}{v}$

Yeh kyun matter karta hai: even 100 km ki distance yeh hai $\frac{100 , 000}{2 \times 1 0 ^{8}} = 500 μ s,$ HFT mein ek lifetime hai jahan edges microseconds ( $μ s$ ) aur even nanoseconds mein measure hote hain.

Figure — Learn about colocation and direct market access

YEH END TO END KAISE KAAM KARTA HAI

HFT firm exchange building ke andar ek colocation rack rent karti hai.
Firm DMA use karti hai (aksar sponsored access, jahan woh broker ki membership/exchange ID use karti hai) taaki uske algorithm ke orders seedhe order book par jayen.
Orders kuch metres ke cross-connect cable se travel karte hain → matching engine → pehle fill hote hain → tiny time advantage se profit (market making spread, arbitrage, etc.).

Common mistakes (steel-manned)

Flashcards

HFT mein colocation kya hai?

Exchange ke data center ke andar/paas server rack space rent karna taaki matching engine tak propagation (distance) latency minimize ho.

Direct Market Access (DMA) kya hai?

Orders seedhe exchange order book par broker ki/exchange ki infrastructure se bhejna bina kisi human dealer ke jo unhe re-key kare.

Colocation kaun si delay attack karta hai vs DMA?

Colocation propagation/distance delay attack karta hai; DMA human/intermediation processing delay attack karta hai.

Optical fiber mein signal ki speed?

Lagbhag

2 \times 1 0^{8}

m/s,

v = c / n

se jahan

n \approx 1.5

Distance d par propagation latency ka formula?

t_{prop} = d / v

Distance

d_{1}

d_{2}

par move karne se kitna time bachta hai?

Δ t = (d_{1} - d_{2}) / v

Exchanges colo mein equal cable lengths kyun dete hain?

Colocation ko fair rakhne ke liye — advantage colo mein hona hai, na kaun sa specific rack.

Firms cities ke beech microwave links kyun use karti hain?

Hawa ka

n \approx 1

hota hai, isliye signals

c

ke karib travel karte hain (fiber ke slow

c /1.5

se faster).

Kya aap colocated ho sakte ho aur phir bhi slow?

Haan — decision time, queueing, aur processing latency rehti hai; colo sirf distance latency kaata hai.

"Sponsored access" kya hai?

DMA jahan ek firm broker ki exchange membership use karti hai orders seedhe apne algo ke under place karne ke liye.

Recall Feynman: ek 12-saal ke bacche ko explain karo

Socho sab log ek dukandaar ko orders chilla rahe hain. Jo insaan dukaan ke bilkul paas khada hai use pehle suna jaata hai — yahi hai colocation (exchange ke super close baithna). Ab socho ki ek dost ko whisper karne ki bajaye jo phir dukandaar ko bataye, tum seedhe dukandaar se baat karo — yahi hai DMA (koi middleman nahi). Agar tum dono karo, tera order sabse pehle dukaan tak pahunchta hai, isliye pehle accha deal pakad lete ho. Real markets mein, "close" aur "no middleman" matlab ho sakta hai kuch millionths of a second se jeetnaa — aur woh tiny bit bahut saara paisa worth hota hai.

Connections

HFT & Advanced Concepts
Latency and Tick-to-Trade
Order Book and Matching Engine
Market Making Strategies
Arbitrage
Speed of Light in Fiber vs Microwave Links
Sponsored Access and Exchange Membership