U.S. stocks finished sharply lower Monday, with the S&P 500 and the Nasdaq logging their worst days since Feb. 8, as concerns about Facebook Inc.’s management of user data sparked a selloff in technology shares.

The Federal Reserve’s coming rate decision has created some uneasiness, as investors are expecting the central bank to adopt a more aggressive path to normalizing monetary policy and lifting borrowing costs.

Check out Need to Know column: Why the case for betting against Facebook is ‘building fast’

How did the main benchmarks fare?

The Dow Jones Industrial Average DJIA, -1.84% fell 335.60 points, or 1.4%, to 24,610.91 with all components, except Boeing Co. BA, -2.97% , finishing in the red. The S&P 500 index SPX, -1.15% dropped 39.09 points, or 1.4%, to 2,712.92, weighed down by a 2.1% decline in the technology sector, the worst performer among the broad-market benchmark’s 11 sectors.

The technology-laden Nasdaq Composite Index COMP, -0.13% lost 137.74 points, or 1.8%, to 7,344.24.

The Dow has turned negative for the year, off 0.4%, while the S&P is up 1.5% and the Nasdaq has advanced 6.4%.

Read:The stock market meltup is over: Morgan Stanley

What drove the markets?

Facebook’s worst drop in nearly four years follows a public outcry over its management of third-party access to users’ information, and weighed on other social-media stocks and the technology sector, which is the best-performing industry this year.

Read: Social-media ETF falls with Facebook set for biggest drop since November 2016

The Federal Reserve has the attention of markets worldwide with an interest-rate hike expected on Wednesday following a two-day meeting of the central bank’s policy group, the Federal Open Market Committee. Higher interest rates can make riskier assets such as stocks less attractive.

Investors also have been worrying this month about a potential global trade war. Concerns about trade friction come as the Trump administration takes a hawkish stance on trade with China and moves ahead with tariffs on foreign steel and aluminum.

See:Web’s creator blasts Facebook, saying it makes his invention easy to ‘weaponize’

Check out:The Fed is hogging the attention, but don’t forget this critical number

Which stocks were in focus?

Shares of Facebook FB, -1.73% skidded 6.8%, their biggest one-day percentage decline since March 26, 2014, when it tumbled 6.9%, as the social-media giant has ignited a firestorm over third-parties’ access to Facebook users’ personal data. Cambridge Analytica, a firm hired to assist President Donald Trump’s 2016 campaign, harvested private information of 50 million Facebook users without their permission. It is also the biggest data breach in Facebook’s history.

Twitter Inc. TWTR, -0.62% fell 1.7% and Snap Inc. SNAP, +0.25% shed 3.5%.

KLA-Tencor Corp. KLAC, +1.19% said it plans to acquire Israeli electronics technology company Orbotech Ltd. US:ORBK in a deal valued at about $3.4 billion and an enterprise value of about $3.2 billion. KLA-Tencor shares were down 3.9%, while those for Orbotech were up 6.8%.

Toronto-based cannabis company Cronos Group Inc.’s shares CRON, -3.21% soared 12% after the company said it has entered a cross-border joint venture with MM Enterprises USA LLC, or MedMen Enterprises, to develop branded products and open stores across Canada.

Apple Inc. AAPL, +3.03% is reportedly designing and making its own display screens for the first time. The iPhone maker’s shares were down 1.5%.

What were strategists saying?

“Equities are lower and Treasury yields are higher and I think it may be signaling that there’s some anxiety abut how hawkish the FOMC will be on Wednesday,” said Brian Jacobsen, senior investment strategist at Wells Fargo Asset Management.

As for the tech slide, Jacobsen declined to talk about specific companies but said trepidation around “what is going on with advertising as a source of revenue” for some companies is one reason why some social-media names are facing selling.

“The market is pricing in a 97.9% likelihood of a rate hike at this meeting. The big question then will be the ‘dot plot’ giving the FOMC members’ estimates of where rates will be at the end of this year and next,” said Marshall Gittler, chief strategist at ACLS Global, in a note.

“I expect that the committee will indeed revise up their forecast for rates, for next year if not for this year, and that this will boost the dollar.”

“Short-term I think we’re just going to have a lot of trepidation until the new Fed chairman speaks,” said Crista Huff, chief analyst at Cabot Undervalued Stocks Advisor.

Read more: What to expect from the new Fed dot plot on interest rates

And see:It’s time for stock-market investors to refocus on the Fed

Is artificial intelligence a better stock picker than humans?

How did other markets do?

European stocks SXXP, -3.24% universally lost ground, while Asian markets finished mixed, with Japan’s Nikkei benchmark NIK, +0.17% down 0.9% as Prime Minister Shinzo Abe faced mounting pressure over a land-sale scandal.

March Madness:Live scores and win probabilities of every NCAA Tournament game

Oil futures US:CLJ8 and the ICE U.S. Dollar Index DXY, -0.13% fell, while gold futures US:GCJ8 settled higher.

—Victor Reklaitis contributed to this report