US STOCKS-Wall St set for lower open as tariff uncertainty prevails; chipmakers slide

By Johann M Cherian and Sukriti Gupta

March 6 (Reuters) - Wall Street's main indexes were set to open lower on Thursday as uncertainty about a trade war unleashed by U.S. tariffs clouded sentiment, while chip stocks slid after Marvell's forecast fanned worries of slowing demand for AI infrastructure.

At 8:43 a.m. ET, Dow E-minis 1YMcv1 were down 368 points, or 0.85%, S&P 500 E-minis EScv1 were down 66.75 points, or 1.14% and Nasdaq 100 E-minis NQcv1 were down 315 points, or 1.52%.

Marvell MRVL.O fell 17.6% in premarket trading after the chipmaker forecast first-quarter sales in line with analysts' average estimate, which failed to excite investors who had expected stronger AI-driven growth.

Peer Broadcom AVGO.O, which is expected to report quarterly results after markets close, fell 4.5%, while Nvidia NVDA.O lost 3.2% and Advanced Micro Devices AMD.O dropped 2%.

Megacaps such as Microsoft MSFT.O and Meta META.O declined over 1% each.

Concerns about overspending and overcapacity in the U.S. AI industry, in the face of China's cheaper DeepSeek models, paused Wall Street's bull rally in January. The tech-heavy Nasdaq .IXIC is now down about 9% from its record high hit in December.

Further, Alibaba's U.S-listed shares BABA.K rose 1.9% after the release of a new reasoning model that the conglomerate said was on par with global hit DeepSeek's R1.

On the trade front, President Donald Trump exempted automakers that comply with existing free trade agreement and sources said the negotiations were ongoing. However, Trump made it clear that he was not calling off his trade war, citing the need for more border controls.

Automakers such as General Motors GM.N and Ford F.N were down over 1.5% each after Wednesday's rise. Tesla TSLA.O fell 2.5% following a report that brokerage Baird named the electric carmaker a 'bearish fresh pick'.

Against the backdrop of trade uncertainty, U.S. stocks have witnessed increased volatility over the past few sessions.

"We're still continuing to see headline risks from the development of tariffs on Mexico and Canada drive U.S. stock prices and until we can get some clarity, we're going to expect some volatility there," said Charlie Ripley, senior investment strategist at Allianz Investment Management

Wall Street's main indexes closed higher over 1% on Wednesday following Trump's announcement. However, the benchmark S&P 500 .SPX is close to levels seen during Trump's election victory and the Russell 200 index .RUT has fallen over 7% since early November. Futures tracking the domestically focused index RTYcv1 fell 1.3% on Thursday.

Multiple reports have suggested that tariff uncertainty has resulted in individuals holding back on consumption and corporate executives staying put on investment decisions, sparking concerns of an impending economic slowdown as inflation stays elevated.

On Thursday, a report that showed weekly jobless claims stood at 221,000 in the week before, lower than expectations of 235,000 allayed some worries about an economic slowdown. Friday's key payrolls data will be crucial for investors trying to gauge the economy's health.

Traders now see the Federal Reserve lowering borrowing costs by 25 basis points for the first time this year in June, according to data compiled by LSEG.

Comments from policymakers Patrick Harker, Raphael Bostic and Governor Christopher Waller are due later in the day.

Zscaler ZS.O rose 3.3% after raising its fiscal 2025 revenue forecast, signaling increasing demand for its cloud-based cybersecurity services.

Kroger KR.N fell 1.5% after its annual profit forecast fell short of expectations.