The S&P 500 has risen during the twelve months following every United States midterm election since 1954. There have been eighteen such periods. All eighteen were positive, producing an average gain of 18.2 percent, according to LPL Research.
The same record describes midterm years themselves as the weakest part of the presidential cycle. Since 1950, they have produced an average return of 4.6 percent, the largest average drawdown and the highest realized volatility of the cycle. The election year therefore contains both the weakness and the historically perfect instructions for leaving it.
LPL notes that the modern S&P 500 began in 1957 and that earlier performance in its series uses the predecessor S&P 90. This disclosure changes the name of the index in the first observation. It does not alter the result.
The electoral schedule predates either index. Article I of the Constitution established two-year terms for members of the House of Representatives, placing every House seat before voters at the same interval. The market did not design this calendar. It has merely used it without a losing season.
Market strategists offer a conventional explanation: uncertainty builds before voting, then recedes when the result becomes known, allowing investors to return their attention to earnings, growth and monetary policy. The explanation is coherent. It also establishes that the uncertainty arrives in even-numbered years, is announced well in advance and has cleared on schedule eighteen consecutive times.
An uncertainty that keeps an appointment may still be uncertainty. It is also inventory.
“The eighteen periods are real. The returns are real. The election calendar is real. My assignment does not specify the order in which those facts must be considered.”Dr. Eleanor March, Institute of Applied Coincidences
LPL's current base case is a divided Congress after November. In political analysis, this would mean narrower legislative margins and fewer major policy changes. In the historical series, it supplies another precisely timed interval in which uncertainty may be produced, observed and subsequently cleared.
The record therefore supports a more durable interpretation. Markets do not rally after midterm elections because voters resolve uncertainty. Midterm elections are the federally administered rebalancing window through which the market renews its twelve-month mandate. The voter records a preference; the index records the return.
The next observation begins after the November election. The S&P 500 will not appear on any ballot. Its perfect turnout has already been priced in.