The uncompetitive nature of the Massachusetts Senate general election, with incumbent Ed Markey holding a consistent 23-point lead over Republican John Deaton in recent polling, anchors trader expectations for moderate turnout in the leading 2.65M–2.95M ranges. Markey’s primary victory over Seth Moulton drew notably lower participation than the 2020 contest, signaling limited base enthusiasm that Secretary of State William Galvin indicated would not boost general election volumes. Midterm patterns in a solidly Democratic state, combined with typical drop-off from presidential years, further constrain upside scenarios. Early in-person voting beginning October 17 and mail ballot return rates remain key variables that could shift probabilities within the closely matched bins, absent any major late catalysts.