13. Interactive Brokers & Alpaca: The Equities Reality Check
In US equities, "market maker" is a legal status you probably can't have — but liquidity-providing strategies are still on the table.
Why you can't just market-make Apple
Registered market makers on lit US equity exchanges must be registered broker-dealers, exchange members (in practice FINRA members too), with minimum net capital and continuous two-sided quoting obligations during market hours. The SEC tried to pull even de-facto liquidity providers into dealer registration with its 2024 dealer-definition amendments — but a federal court vacated those rules in November 2024 and the SEC abandoned its appeal in early 2025, so the older, narrower dealer framework governs. Retail accounts at IBKR or Alpaca still meet none of the registered-MM criteria — and Reg NMS (Rule 611's trade-through protection, Rule 610's access-fee cap, Rule 612's penny tick) shapes the playing field around protected quotes you can't directly join as a dealer. That terrain is shifting too: a half-penny tick for tick-constrained stocks and a much lower access-fee cap are adopted but delayed to late 2027, and in mid-2026 the SEC proposed rescinding Rule 611 outright. Rules quoted here are the operative mid-2026 ones; re-check before building anything on them.
What you can do
- Liquidity-providing limit strategies. Post non-marketable limit orders; on IBKR's tiered pricing, exchange maker rebates are passed through to you. With Post-Only routing to rebate venues, a patient strategy can run a maker-style book — at far lower frequency than true MM. (The old Pattern Day Trader rule — $25k minimum for frequent day-trading — was retired in June 2026; brokers now apply risk-based intraday margin instead, so the constraint is your margin capacity, not a day-trade counter.)
- Options as the real spread game. Options markets are where wide spreads still exist for sophisticated retail. The professional MM toolkit there is the Greeks: quote options, delta-hedge with the underlying, manage gamma (short-gamma positions lose in big moves and must buy high/sell low to rehedge) and vega (IV exposure, hedged with offsetting options). Several options exchanges still allocate fills pro-rata with customer priority — size, not speed, earns allocation there.
- Alpaca as an execution lab. Commission-free API equities (now trading 24/5) and 24/7 crypto spot make Alpaca a natural sandbox for signal-driven liquidity provision — closer to "patient limit-order alpha" than market making proper.
12. Binance: The Deep End of Crypto
The deepest books, the thinnest spreads, the fastest competitors — and a fee ladder that decides who's allowed to play.
14. Which Algorithm for Which Market
Sports, stocks, and crypto are three different physics. Matching the algorithm to the price process is half the job.