Oct 08, 2026 by Offer

SIG Doubling Bet Interview 2027: Accept or Reject the Double?

Accept the double only if your win probability is above 50%. Doubling a $10 bet creates a fresh $20 swing: EV = 20p − 20(1−p) = 40p − 20, positive exactly when p > 50%. This "sig double the bet probability" question is commonly reported by candidates as an expected-value test under doubling stakes.

SIG Double The Bet Probability: What This Question Assesses

The question tests whether you price the doubled bet as a brand-new bet rather than anchoring on the original $10. Many candidates hesitate because "double" sounds aggressive, but the math is clean: after the double is offered, the only thing that matters is whether the new stake has positive expected value. SIG wants traders who re-price risk from scratch.

SIG Double The Bet Probability: How to Answer

Restate the doubled bet. Accepting means you now stand to win $20 or lose $20 — the original $10 is sunk and irrelevant to the decision.
Write the expected value. EV = p × $20 − (1 − p) × $20 = 40p − 20.
Solve for the breakeven. 40p − 20 > 0 gives p > 0.50. At exactly 50% you are indifferent; above it, accepting is correct.
Note the intuition. The double is symmetric — equal amounts won or lost — so the threshold is the same 50% as the original bet. The doubling changes the size, not the fairness.

Sample line: "Once doubled, it's a fresh $20 bet — I accept whenever my win probability is above 50%, since expected value is 40p minus 20."

Common Mistakes

Treating the original $10 as relevant — it is sunk; only the new $20 swing matters.
Demanding a higher threshold like 60-70% because doubling "feels" riskier, when the math says 50%.
Confusing this with doubling down in blackjack, where strategy tables apply — here it is a pure expected-value call.

Candidates who answer on feel rather than EV get filtered fast in SIG's game-theory rounds. Drill symmetric-bet breakevens until 50% is your instant answer. Question formats may vary by role and region; confirm on SIG's official careers page.

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FAQ

What minimum win probability makes accepting the double correct? Just above 50%. At exactly 50% the doubled bet is fair; above 50% it has positive expected value.

Why doesn't the original $10 bet size matter? Because it is already committed. The decision only concerns the new $20 swing created by the double.

Is this a real SIG interview question? Doubling and bet-sizing questions are commonly reported by candidates in SIG interviews, though exact scenarios may vary by role and region.

Does risk aversion change the answer? In theory a risk-averse player might demand slightly more than 50%, but the question asks for the mathematically correct threshold — answer 50% and mention risk preference only as a caveat.

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