The S&P 500 rose in the 12 months after 18 of the 19 U.S. midterm elections held since 1950, and was flat after the 19th, by this publication's count of the index data compiled by Yale economist Robert Shiller. Americans vote in the 20th such election on Tuesday, 3 November 2026.

That record is often repeated around Election Day. We did the arithmetic ourselves, from a primary data series, and found that it holds up, with two qualifications. The sample is small, and the gap it shows is as much about the years that came before as about the vote. Past returns do not predict future ones. Polls close tonight, and no result is known.

Every one of the 435 seats in the House of Representatives is up, as it is every two years under Article I of the Constitution. In the Senate, 33 seats are up in the regular cycle, according to the Senate's own list of Class II senators, whose terms end on 3 January 2027. Two more, both held by Republicans, are special elections in Ohio and Florida, Ballotpedia reported, for 35 in all. Thirty-six states elect governors, along with Guam, the Northern Mariana Islands and the U.S. Virgin Islands, according to the National Governors Association.