Facebook CEO Mark Zuckerberg was surrounded by members of the media on Tuesday as he arrived to testify before a Senate joint hearing about the company’s use and protection of user data.

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The '50 Cent' trader who bets on market volatility says a financial 'earthquake' is coming. "We are confident that the earthquake will happen, more confident than we have been that it will happen in months, not years," Jonathan Ruffer, the cofounder of Ruffer LLP, the firm behind a series of trades last year betting on a rise in market volatility via the purchase of 50-cent options contracts, said in a quarterly investment note to clients.

The world has never been in this much debt. Global debt levels rose by $21 trillion last year to $237 trillion, the highest level on record, according to the Institute of International Finance.

The Russian ruble is on track for its worst week since 1999. The ruble has tumbled more than 10% versus the dollar this week after the Trump administration on Friday imposed new sanctions on 24 wealthy Russians and government officials as well as over a dozen Russian-controlled entities.

Chinese inflation comes up short. Consumer prices in China fell 1.1% month-over-month in March, missing the 0.5% decline that economists were anticipating. The data was most likely distorted by temporary factors related to the Lunar New Year.

One of Germany's richest men is missing in the Swiss Alps. The German billionaire Karl-Erivan Haub, who is the owner and CEO of the retail group Tengelmann, went missing during a ski trip in the Swiss Alps last week.

Mark Zuckerberg survived 5 hours of relentless questioning from Congress. The Facebook CEO testified Tuesday at a US Senate joint committee hearing on the Cambridge Analytica data scandal. He will be back on Capitol Hill for more testimony on Wednesday.

Fewer companies are getting venture-capital money. Venture-capital investing jumped 18.5% to $28.2 billion in the first quarter, but the 1,693 startups that got funding in the period was the lowest since at least 2011, according to a joint report from PitchBook and the National Venture Capital Association.

Stock markets around the world trade mixed. China's Shanghai Composite (+0.56%) led the gains in Asia, and France's CAC (-0.3%) lags in Europe. The S&P 500 is set to open lower by 0.69% near 2,638.

Earnings reporting is light. Bed Bath & Beyond is set to report after markets close.

US economic data trickles out. CPI will be released at 8:30 a.m. ET, and the minutes from the March Federal Open Market Committee meeting will cross the wires at 2 p.m. ET. The US 10-year yield is down 1 basis point at 2.79%.