10 things you need to know before the opening bell

Stocks are entering the 'frothy territory' reached before the last 2 crashes. Equity market cap as a percentage of gross domestic product has returned to levels last seen in 2000 and 2008, according to Deutsche Bank.

The Bank of England warns UK banks not to 'return to the punchbowl.' Speaking Monday, Sam Woods, CEO of the Bank of England's Prudential Regulation Authority, warned some banks are loosening their internal controls to create credit and boost risk.

Foreign investors went on a buying spree across Asia. Foreign investors poured $63.6 billion into Asian bonds and stocks during the first half of 2017, making for the biggest net inflow since the second half of 2012, according to new research from Australian bank ANZ.

Ethereum tumbles below $200. The cryptocurrency tumbled more than 15% to a low of $175 an ether on Tuesday before recovering a good chunk of its losses. Currently, it's down 6.6% at $196.

Snap falls below its IPO price. Shares of the social media company hit $16.99 apiece on Monday, a penny less than their March 1 initial public offering price.

Amazon Prime Day is here. JPMorgan could rake in $1 billion over the 30-hour event, according to analysts at JPMorgan.

UBS says its London bankers could move to one of 3 places. "I think Frankfurt is a location of choice. There are different, other locations that could come into consideration," UBS Chief Executive Sergio Ermotti said in an interview with CNBC. Other destinations include Amsterdam or Madrid.

Stock markets around the world trade mixed. Hong Kong's Hang Seng (+1.48%) led the gains in Asia and Britain's FTSE (-0.7%) trails in Europe. The S&P 500 is set to open down 0.17% near 2,423.

Earnings season kicks off. Pepsi reports ahead of the opening bell.

US economic data is light. JOLTS Job Openings and wholesale inventories will be released at 10 a.m. ET. The US 10-year yield is up 1 basis point at 2.39%.