10 things you need to know before the opening bell (SPY, SOX, QQQ, DIA, SNAP)

Trump says Yellen may stay on as Fed chair after her term expires. President Donald Trump told The Wall Street Journal that Federal Reserve Chair Janet Yellen was "not toast" and that it was too early to say whether he would ask Yellen to stay in the role after her term expires in 2018.

Trump talks down the dollar. "I think our dollar is getting too strong, and partially that's my fault because people have confidence in me," Trump told The Wall Street Journal.

China's trade data beats. Exports surged by 16.4% in US dollar terms as imports grew by 20.3%, making for a surplus of $23.93 billion in March. Economists were expecting a $10 billion surplus after February's $9.15 billion deficit.

Iron ore is in free fall. The price plunged 8.5% to $68.04 a tonne on Wednesday, and it has lost 16.6% over the past five sessions. Iron ore is down 28.3% since its multiyear high of $94.86 a tonne on February 21.

Warren Buffett dumps Wells Fargo stock to avoid Fed regulations. Buffett's Berkshire Hathaway sold 9 million shares, worth about $480 million, of Wells Fargo stock to avoid owning more than 10% of the company and therefore being subject to increased regulation from the Fed.

Snap sets its first earnings call. The maker of the popular social-media app will conduct its first quarterly earnings call May 10. It is unclear whether CEO Evan Spiegel will participate.

Robert De Niro is playing Bernie Madoff in a new movie. HBO's "The Wizard of Lies" also features Michelle Pfeiffer as Madoff's wife, Ruth. The movie premieres May 20.

Stock markets around the world are lower. Japan's Nikkei (-0.7%) trailed in Asia, and Britain's FTSE (-0.6%) lags in Europe. The S&P 500 is set to open down 0.3% near 2,338.

3 big banks kick off earnings season. Citigroup, JPMorgan, and Wells Fargo are set to release their quarterly results ahead of the opening bell.

US economic data flows. PPI and initial jobless claims will be released at 8:30 a.m. ET before University of Michigan consumer confidence crosses the wires at 10 a.m. ET. The US 10-year yield is down 2 basis points at 2.22%.