High-Frequency Trading (HFT)

HFT firms operate at speeds incomprehensible to human traders. A typical HFT system processes market data, runs algorithms, and submits orders in under 10 microseconds — about 100,000 times faster than a human blink.

The technology stack: HFT firms co-locate servers directly inside exchange data centers (paying $5,000-$20,000/month per rack) to minimize latency to microseconds. They use custom hardware including FPGAs (Field-Programmable Gate Arrays) that process data in hardware rather than software, shaving nanoseconds off execution time. Network connections use microwave towers or hollow-core fiber optics for the fastest possible signal transmission between exchanges.

The profit model: Individual HFT trades capture tiny profits — often fractions of a cent per share. But executed millions of times per day across thousands of stocks, these fractions compound into significant daily revenue. A top HFT firm might execute 10 million trades per day with an average profit of $0.002 per share, generating $20,000-$100,000 in daily profit.

Order-to-trade ratio: HFT firms submit and cancel far more orders than they execute. A 50:1 ratio (50 orders submitted for every 1 filled) is common. This rapid order placement and cancellation is how they probe the market for liquidity and adjust prices in real time.

Market making: HFT firms continuously post buy and sell orders, earning the bid-ask spread. On a stock with a $0.01 spread, a market maker buying at $100.00 and selling at $100.01 earns a penny per share. At millions of shares per day, this adds up. HFT market makers provide roughly 50% of displayed liquidity in US equity markets.

Statistical arbitrage: Algorithms detect tiny mispricings between correlated securities — for example, if SPY moves before an individual stock adjusts, the HFT firm trades the lagging stock for a small profit. These correlations hold for milliseconds before other firms notice.

Latency arbitrage: When the same stock is listed on multiple exchanges, prices can differ for microseconds. HFT firms with faster connections race to buy at the lower price and sell at the higher price. IEX exchange was specifically designed with a speed bump to reduce this practice.

Event-driven: Algorithms parse economic data releases, earnings announcements, and news feeds in microseconds and trade before human traders can react. Natural language processing models extract sentiment from text and trade on the signal.

Rebate capture: Exchanges pay rebates ($0.002-$0.003/share) for providing liquidity. HFT firms design strategies specifically to earn these rebates while minimizing directional risk.

Benefits for retail traders: HFT market making has dramatically tightened bid-ask spreads. In the 1990s, spreads on NYSE stocks were often $0.125 (1/8 of a dollar). Today, most liquid stocks have $0.01 spreads. This saves retail traders money on every trade. HFT also provides deeper liquidity, making it easier to enter and exit large positions.

Challenges for retail traders: HFT firms have a structural speed advantage. They can detect large retail orders and adjust prices before the full order is filled, a practice called adverse selection. Payment for order flow (PFOF) routes most retail orders through HFT market makers like Citadel Securities, which may execute at slightly worse prices than the best available on exchanges.

What retail traders should know: You cannot compete with HFT on speed, and you do not need to. HFT profits come from microsecond edges across millions of trades. Retail traders profit from analysis, patience, and holding periods of minutes to months — a completely different game. Focus on:

• Using limit orders instead of market orders to avoid adverse selection
• Trading liquid stocks with tight spreads where HFT competition benefits you
• Avoiding illiquid names during volatile periods when spreads widen
• Not trying to scalp for pennies (HFT will win that game every time)