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Nike ( NKE ) dips on bleak revenue outlook

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FedEx ( FDX ) tumbles after results, outlook

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Boeing ( BA ) jumps after fighter jet contract award

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Indexes up: Dow 0.08%, S&P 0.08%, Nasdaq 0.52%

(Adds prices, volume data)

By Chuck Mikolajczak

NEW YORK, March 21 (Reuters) - The S&P and Dow eked out slight gains on Friday, erasing earlier losses after comments from U.S. President Donald Trump provided hope that previously announced tariffs expected to begin in early April may not be as burdensome as feared.

Trump said there will be flexibility on tariffs and that his top trade chief plans to speak with his Chinese counterpart next week. The president also reiterated his plan to use duties as a way to narrow the U.S. trade deficit with China.

Markets have been under pressure in recent weeks as changing announcements about the timing and size of tariffs have clouded the outlook for corporate profits as well as the Federal Reserve's monetary policy path.

Stocks have shown some signs of bottoming this week, however, with the S&P climbing more than 1% on Wednesday in the wake of the Fed's latest policy announcement. The central bank kept rates unchanged and signaled two cuts were likely this year.

Even so, Michael Arone, chief investment strategist for the U.S. SPDR Business at State Street Global Advisors in Boston, said it was concerning that investors' attempts to rally the stock market had largely failed.

"The reasons are the continued uncertainty around trade policy from the Trump administration, continued concerns about a U.S. economic growth scare and ultimately uncertainty about what the path of monetary policy looks like," Arone said.

Chicago Federal Reserve President Austan Goolsbee said the central bank needs more time to "sort through" how Trump's policies play out in the economy, while New York Fed President John Williams echoed Goolsbee's comments and said there was no rush to change monetary policy right now.

The Dow Jones Industrial Average rose 32.03 points, or 0.08%, to 41,985.35, the S&P 500 gained 4.67 points, or 0.08%, to 5,667.56 and the Nasdaq Composite gained 92.43 points, or 0.52%, to 17,784.05.

The S&P was down as much as 1.06% earlier in the day.

For the week, the S&P 500 gained 0.5%, the Nasdaq rose 0.17%, and the Dow climbed 1.2%. It was the largest weekly gain for the Dow in two months, while the Nasdaq and S&P 500 managed to barely snap four-week streaks of declines.

With earnings season set to begin next month, multiple companies have been reducing their forecasts. FedEx ( FDX ) slumped 6.45% after the package delivery company cut its full-year profit and revenue forecasts, citing continued weakness and uncertainty in the U.S. industrial economy.

Peer UPS declined 1.61%. Delivery firms are often seen as a bellwether for the global economy given their reach into a wide swath of different industries.

The delivery companies weighed on the Dow Jones Transport Index, which dropped as much as 2.7% during the session before closing down only 0.2%.

Nike ( NKE ) slid 5.46% as the worst performer among Dow Industrial components after the sports apparel maker projected a sharper decline in fourth-quarter revenue than analysts had anticipated.

The materials sector, off 1% on the session, was weighed down by a 5.78% tumble in shares of Nucor Corp ( NUE ) after the company forecast first-quarter profit below estimates.

Boeing ( BA ) climbed 3.06% after Trump awarded the planemaker a contract to build the U.S. Air Force's most sophisticated fighter jet, beating out rival Lockheed Martin ( LMT ) , which slumped 5.79%.

Friday's session also marked the simultaneous expiry of quarterly derivatives contracts tied to stocks, index options and futures, also known as "triple witching", which can exacerbate market volatility.

Declining issues outnumbered advancers by a 1.93-to-1 ratio on the New York Stock Exchange and by a 1.42-to-1 ratio on Nasdaq.

The S&P 500 posted nine new 52-week highs and 16 new lows, while the Nasdaq Composite recorded 38 new highs and 188 new lows.

Volume on U.S. exchanges was 21.05 billion shares, compared with the 16.47 billion average for the full session over the last 20 trading days, and the busiest trading day since January 7.

(Reporting by Chuck Mikolajczak; additional reporting by Reporting by Pranav Kashyap and Johann M Cherian in Bengaluru; Editing by Nia Williams)