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By Purvi Agarwal and Johann M Cherian

May 6 (Reuters) - Wall Street's main indexes fell on Tuesday after U.S. President Donald Trump's latest plans for pharma tariffs renewed worries of the impact of a trade war, while some downbeat corporate results also weighed on investor sentiment.

Trump said late on Monday that he would announce pharma tariffs over the next two weeks, his latest action on levies that have roiled global financial markets over the past months.

Eli Lilly LLY.N and Merck MRK.N slipped about 2.4% each, while Pfizer PFE.N was down 1.7% after the news, which offset optimism around Trump's order aimed at reducing the approval time for pharmaceutical manufacturing plants.

Tariff-driven uncertainty has led consumers, businesses and even the U.S. Federal Reserve to adopt a wait-and-watch mode as they struggle to navigate the tariffs and gauge their impact.

Ford Motor F.N was the latest to suspend its annual outlook on Monday, joining a host of companies that withdrew their forecasts in April. The carmaker's shares reversed premarket losses and were last up about 1% in choppy trading.

"The biggest thing that stands out (this earnings season) is that CEOs are concerned about the uncertainty that's coming out (of) Washington, D.C. with respect to global trade," said Adam Sarhan, chief executive of 50 Park Investments.

At 09:55 a.m. ET the Dow Jones Industrial Average .DJI fell 435.80 points, or 1.06%, to 40,783.03, the S&P 500 .SPX lost 61.98 points, or 1.10%, to 5,588.40, and the Nasdaq Composite .IXIC lost 240.21 points, or 1.35%, to 17,604.03.

Most S&P 500 sectors were trading in the red, with healthcare .SPXHC and info tech .SPLRCT the biggest losers, down 1.4% and 1.7%, respectively.

Data analytics firm Palantir's PLTR.N shares fell 13.5% to the bottom of the S&P 500 as investors were unimpressed by the company's modest revenue beat and in-line profit.

The Fed starts its two-day meeting on Tuesday, with the central bank widely expected to stay put on interest rates. Comments from policymakers will be scrutinized for any clues hinting at where they stand on monetary policy easing this year.

Traders see about 79 basis points of policy easing by the end of 2025, with the first cut coming in July, according to data compiled by LSEG.

The Trump administration suggested last week that potential deals with trading partners were underway, but markets have seen no concrete results on that front. Wall Street closed lower on Monday, with the benchmark S&P 500 snapping a nine-session winning streak.

Against the uncertain trade backdrop, businesses boosted imports of goods in March, pushing the country's trade deficit to a record high of $140.5 billion.

DoorDash DASH.O was down 7.5% after the meal delivery firm said it would buy Deliveroo ROO.L in a deal valuing the British rival at about 2.9 billion pounds ($3.86 billion). The U.S. firm's quarterly revenue missed estimates, disappointing investors.

Declining issues outnumbered advancers for a 3.03-to-1 ratio on the NYSE and a 3.31-to-1 ratio on the Nasdaq.

The S&P 500 posted three new 52-week highs and six new lows, while the Nasdaq Composite recorded nine new highs and 56 new lows.

($1 = 0.7505 pounds)

(Reporting by Purvi Agarwal and Johann M Cherian in Bengaluru; Editing by Pooja Desai, Shinjini Ganguli and Shounak Dasgupta)

((Purvi.Agarwal@thomsonreuters.com))