Estimating a Prop Firm's Annual Revenue

"Roughly how much revenue does a mid-sized proprietary trading firm generate in a year?" This is a favorite because it's directly about the interviewer's own industry, there's no hiding behind "I don't know finance," and the assumptions you pick reveal how much you understand about how a prop firm actually makes money. The chain has two natural routes: from capital and returns, or from headcount and per-trader output. Building both and comparing is the strongest answer.

Route 1: capital times return on capital

A mid-sized firm might deploy, say, $500 million to $1 billion of capital (own capital plus leverage) across its strategies. Prop trading returns on deployed capital are typically far higher than a long-only fund's, because the capital is turned over rapidly and leveraged, a reasonable anchor is 20–40% annualized return on deployed capital for a firm running market-making and stat-arb style strategies. Taking $700 million and 30%: $700 \times 0.30 = 210$, i.e. $210 million in annual trading revenue (before costs).

Route 2: headcount times revenue per trader

A mid-sized firm might employ 150–250 traders and quantitative researchers directly involved in generating P&L. Revenue per senior trader at a well-run prop firm is commonly cited in interview folklore as somewhere in the $1–2 million/year range (this varies hugely by strategy and seniority, but it's a workable anchor), while junior traders and researchers contribute less individually but add headcount. Blending across seniority, call it an average of $1 million/trader across 200 traders: $200 \times 1 = 200$, i.e. $200 million.

Route 1 ($210M) and Route 2 ($200M) land within 5% of each other, strong agreement from two structurally independent chains, one anchored in capital markets, the other in headcount economics.