The firm Stress Desk re-prices every position through equity style factors — the wrong risk model for a risk-arbitrage book. An arb position's P&L is driven by one binary event: the deal closes (collect the spread) or it breaks (gap down to the unaffected price). And breaks cluster. This monitor joins the firm book's Merger-Arb sleeve to the Spread Desk's per-deal record and models the book on its correct axis — cluster break, worst-quartile break, deal-risk-weighted expected P&L and full-close carry.