California's congressional map, redrawn via Proposition 50 and approved by voters in late 2025, forms the primary driver of trader expectations, shifting several formerly Republican-leaning districts toward Democrats and projecting a net gain of three to five seats from the current 43 held. June primaries clarified general-election matchups in targeted Central Valley and San Diego-area districts, with Democrats advancing competitive candidates in most while Republicans retained viable paths in at least one or two. The broader midterm environment, with voters assessing the sitting administration, adds modest upside reflected in slim probabilities for 49 or more. Current pricing places 48 seats as the consensus outcome, consistent with forecasts showing Democrats favored to capture four or five of the five exposed Republican seats while holding their existing majority.