Dan Koh leads the MA-06 Democratic primary market at 74.5% amid an open-seat contest created by Seth Moulton’s Senate bid. Traders cite his substantial fundraising edge, with over $3.5 million raised by late March compared to Tram Nguyen’s roughly $430,000, along with prior federal experience and broader name recognition. A late-May campaign poll showed Nguyen ahead at 28% to Koh’s 18% among likely Democratic primary voters, yet market pricing remains anchored on Koh, reflecting assessments of resource advantages and historical patterns in crowded Massachusetts primaries. Nguyen holds second at 20.3% on momentum from recent internal surveys, while lower-priced contenders trail due to limited visibility and funding. The September 1 primary leaves time for shifts in endorsements or voter turnout in the North Shore district.