Keir Starmer’s review into Peter Mandelson’s security concerns has traders reevaluating his political future. “Starmer out by December 31, 2026” is now at 64.5% YES, up from 62% a day ago.

The review has pushed resignation odds higher, with the June 30, 2026 market at 35% YES, up from 18% a week ago. Traders are pricing in potential fallout from the review, particularly if damaging details surface. The sharpest move is in the December 31, 2026 market, which spiked 4 points last night.

Market depth on the December contract is $19,921 to move it 5 points, showing substantial institutional positioning. The June market is thinner at $3,221 depth, making it more vulnerable to large trades but also reflecting growing trader focus on the nearer-term exit window.

At 35¢, a YES share for June 30 pays $1, a potential 2.9x return if Starmer exits by then. Traders taking that bet need to believe the review delivers a fatal blow to his leadership within 71 days.

Watch for statements from Labour’s NEC or key MPs, and Mandelson’s responses. These will signal whether the market’s current trajectory reflects a real threat to Starmer or is just noise.

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