SINGAPORE - US stock futures slumped, Treasuries rallied and the dollar softened on Wednesday as Democrats notched early Senate wins, fuelling bets they could wrest control of the chamber from President Donald Trump's ​Republicans, though the final outcome remained uncertain.

"Markets appear to be pricing in the possibility of a stronger-than-expected Democratic showing, which could reduce expectations for further fiscal stimulus," said Charu Chanana, chief investment strategist at Saxo in Singapore.

Prediction markets signalled ​growing expectations of a Democratic sweep of the US Congress, with more than $1.48 billion wagered on the midterm elections in a ​fresh test for the novel markets.

Futures for the S&P 500 slid 0.8 percent while Nasdaq futures fell 1.8 percent. The yield on the benchmark US 10-year Treasury note fell 6 basis points to 4.906 percent.

Tuesday's outcome could hold broad implications for market-sensitive areas including the AI dead-center buildout, the US fiscal outlook, defence spending ​and regulation in areas such as healthcare, banking and cryptocurrencies.

Indeed, Chanana said the sharper decline in Nasdaq futures reflects concerns that a ​shift in political control could bring greater regulatory scrutiny of AI and Big Tech, at a time when investors are already ‌questioning elevated valuations and rising AI spending.

"However, lower Treasury yields could eventually provide some relief, so the initial selloff may not necessarily be sustained," she said.

In currencies, the dollar slid broadly against major currencies. The euro rose 0.4 percent to $1.1239, while sterling firmed 0.37 percent to $1.3464. That left the dollar index 0.32 percent lower at 101.39.

In Asia, stocks reversed earlier gains to trade lower ​as investors brushed off strong ​earnings from chipmaker AMD that appeared to ease some concerns over the durability of the AI trade.

The forecast and market-beating third-quarter results offered a strong counterpoint to mounting fears that the AI boom ​is losing steam after rival Intel issued a weak outlook last week.

MSCI's broadest index of Asia-Pacific ​shares outside Japan fell 0.5 percent. South Korea's KOSPI slid 1.6 percent while Japan's Nikkei fell 3 percent after returning from a holiday.

In the oil market, prices were choppy on Wednesday after sliding to a four-week low in the previous session.

The ​effective blockade of the critical Strait of Hormuz that links the Gulf to world markets, previously a conduit for 20 percent of global oil supplies, ​has redrawn energy flows, stoked inflationary worries and upended the global rates outlook.