US stock futures were little changed as Americans headed to the polls on Election Day, with control of both chambers of Congress at stake and investors weighing mounting risks to the artificial intelligence trade.

S&P 500 futures were muted, while contracts on the Nasdaq 100 rose 0.3% as of 7:30 a.m. in New York, clawing back earlier losses. Technology shares attempted a tentative rebound a day after entering a correction.

The election adds another layer of uncertainty to an already fragile market backdrop. Polymarket is pricing roughly a 95% probability of Democrats taking the House of Representatives and about a 77% chance of a Senate victory, pointing to a potential sweep of both chambers. The divergence between opinion polls and prediction-market expectations has drawn fresh attention as investors position for the outcome.

History, however, has generally favored stocks following midterm elections. Large-cap equities have gained about 15% on a market-cap-weighted basis and 16% on an equal-weighted basis in the six months after midterms since 1982, according to Morgan Stanley. Both measures have advanced roughly 22% over the subsequent year.

“For all the prognostications and reactions to tonight’s results, here’s the key stat to remember: While past performance doesn’t guarantee future results, since 1950, so 76 years, the S&P 500 has never been lower 12 months after a midterm election, and that is the most notable point of all for clients,” said Tom Essaye, founder of The Sevens Report.

Still, investor positioning suggests caution is building. Investors added a further $9.6 billion in net new short positions in S&P 500 futures last week, bringing overall positioning close to neutral, according to Citigroup strategists. Nasdaq futures saw a similar trend. Positioning in Russell 2000 futures improved, driven by short-covering and suggesting investors have become less bearish on US small-cap stocks, Citi strategists led by David Chew said.

Concerns about the sustainability of AI spending are adding to the unease. As tech heavyweights increasingly turn to bond markets to finance their AI investments, some of the world’s largest asset managers are warning that the boom risks is developing into a bubble. Pacific Investment Management Co. Chief Executive Officer Emmanuel Roman and Bain Capital Chair John Connaughton are among investors flagging the possibility of an eventual downturn following the sector’s rapid expansion, even as Wall Street executives continue to tout its long-term potential.

In single stocks, Apple Inc. added to the pressure after its latest quarterly results disappointed on several key metrics, including revenue in China. Analysts have also pointed to margin pressures and slowing growth in its services business, raising questions about the ability of another major tech giant to sustain investor expectations. Shares of the iPhone maker slipped nearly 4% before market open.

There are, however, signs that market leadership is broadening beyond the largest tech companies. The S&P 500 fell just 0.9% in October despite a sharp selloff in big tech stocks, as strength in other parts of the market helped cushion the decline.

Market breadth recovered from September’s weakness, while energy and defensive sectors including consumer staples, utilities and healthcare offset losses in tech and communications. Low-volatility stocks also led factor performance, reversing some of their declines in the first half of the year, Bloomberg Intelligence’s Christopher Cain wrote in a note.

The earnings backdrop has remained relatively resilient. Companies representing about 70% of the S&P 500’s market capitalization have reported third-quarter results, with 84% beating earnings estimates and 13% missing expectations.