10 things you need to know before the opening bell (SPY, SPX, QQQ, DIA, LUV, IBM, HMNY)

Tax Day was postponed for some. Parts of the Internal Revenue Service's tax-filing system went down Tuesday, and Americans who weren't able to file at the last minute were given another day to meet the deadline.

UK inflation hits its lowest level in a year. Consumer prices in Britain rose 2.5% in March, down from 2.7% in February, as prices of women's clothing rose slower than usual.

China's property-market slowdown looks as if it's over. Home prices rose in 55 of the 70 cities monitored, according to data released Wednesday by China's National Bureau of Statistics.

New York's attorney general launches an investigation into crypto. New York Attorney General Eric Schneiderman has requested information from 13 crypto exchanges in an effort to "increase transparency and accountability as it relates to the platforms retail investors rely on to trade virtual currency, and better inform enforcement agencies, investors, and consumers," a news release said.

The Southwest passenger who died after major engine failure was a Wells Fargo VP. The passenger who died aboard Southwest Flight 1380 has been identified as Jennifer Riordan, 43, a vice president of community relations at Wells Fargo.

IBM's guidance disappoints. The enterprise giant beat on both the top and bottom lines, but shares fell 5% in after-hours trading Tuesday after the company forecast full-year 2018 earnings of $13.80 a share, which missed Wall Street's expectation of $13.84.

There's 'substantial doubt' MoviePass can stay in business. MoviePass' owner, Helios & Matheson Analytics, filed a 10-K to the US Securities and Exchange Commission that showed a loss of $150.8 million last year; and its auditor, Rosenberg Rich Baker Berman & Co., says there is "substantial doubt about the Company's ability to continue as a going concern."

Stock markets around the world are higher. Japan's Nikkei (+1.42%) led the overnight gains in Asia, and Britain's FTSE (+0.74%) is out front in Europe. The S&P 500 is set to open up 0.1% near 2,709.

Earnings reports keep coming. Morgan Stanley reports ahead of the opening bell, and American Express releases its quarterly results after markets close.

US economic data is light. The Fed's Beige Book will cross the wires at 2 p.m. ET. The US 10-year yield is unchanged at 2.83%.