10 things you need to know before the opening bell

Richmond Fed President Jeffrey Lacker resigns. Lacker resigned effective Tuesday after apparently admitting to leaking secret, market-sensitive information about key discussions on interest-rate policy within the central bank to the consulting firm Medley Global Advisors. Business Insider's Pedro Nicolaci da Costa gives his firsthand account of the matter.

Obamacare is more popular than ever. A new Gallup poll found that 55% of respondents approved of Obamacare. That's the first time since Gallup began asking about Obamacare back in November 2012 that its approval rating had climbed above 50%.

Zuma receives the backing of his party. South African President Jacob Zuma has received the backing of his African National Congress party, which has rejected calls for Zuma to step down, Reuters says. The South African rand is weaker by 1.5% at 13.8350 per dollar.

Europe's economy had its best quarter in 6 years. The latest PMI surveys from IHS Markit showed March's composite reading of 56.4 was the best pace of expansion since the first quarter of 2011.

Theresa May is trying to get Saudi Aramco to list in London. The UK prime minister brought the London Stock Exchange's chairman, Xavier Rolet, to a meeting with Saudi energy minister Khalid al-Falih, The Times says.

ChemChina's $43 billion takeover of Syngenta receives EU approval. First, ChemChina must divest "a significant part" of its Adama unit's pesticide business, Bloomberg says.

Snapchat's lead underwriter made an error analyzing the stock. Morgan Stanley published an equity research note on Snapchat and gave the stock a $28 target. A day later the bank issued a correction, changing important metrics in the model but not the $28 target.

Stock markets around the world are up. China's Shanghai Composite (+1.5%) led in Asia, and Spain's IBEX (+0.4%) is out front in Europe. The S&P 500 is set to open little changed near 2,358.

Earnings reports trickle out. Monsanto and Walgreens Boot Alliance report ahead of the opening bell, while Bed Bath & Beyond and Yum China release their quarterly results after markets close.

US economic data is heavy. ADP Employment Change will be released at 8:15 a.m. ET before Markit PMIs and ISM nonmanufacturing cross the wires at 9:45 a.m. ET and 10 a.m. ET. The minutes from the March Federal Open Market Committee meeting are due out at 2 p.m. ET. The US 10-year yield is unchanged at 2.36%.