10 things you need to know before the opening bell

Here is what you need to know.

Chinese stocks tank to their lowest level since January 2016. China's Shanghai Composite fell 1.34% on Friday, settling at its lowest level since January 28, 2016, as trade war fears and a domestic deleveraging campaign by Chinese authorities weighed.

The lira is tumbling after the US said it's ready to kick its battle against Turkey up a notch. The Turkish lira plunged as much as 8.77% Friday morning after US Treasury Secretary Steven Mnuchin threatened further sanctions against Turkey if it does not release detained American pastor Andrew Brunson.

The legendary investor who predicted the past 2 bubbles breaks down how the 9-year bull market will end. Jeremy Grantham, the cofounder and chief investment strategist at the $71 billion Grantham, Mayo, & van Otterloo, tells Business Insider's Joe Ciolli that he was convinced a severe stock-market bubble burst earlier this year - until President Donald Trump's trade war injected skepticism into the market - and that considerable pain for investors may still be in store.

The biggest tech companies are about to undergo a major reshuffling on the stock market. On September 28, S&P Dow Jones Indices and GICS will create a new sector for tech, media, and telecoms companies that will include Facebook and Netflix.

Elon Musk says he has no plans to step down as Tesla chairman and CEO. Musk told the New York Times that he plans on keeping his dual roles, but added "if you have anyone who can do a better job, please let me know. They can have the job."

Nvidia cuts its guidance. The chipmaker said Thursday that it sees third-quarter revenue of around $3.25 billion, down from its previous estimate of $3.34 billion, sending shares lower by about 6% in after-hours trading.

Walmart's surging stock added $12 billion to the Walton family's wealth. The Walton family saw its net worth surge to $163.2 billion Thursday - up $11.6 billion - after Walmart shares jumped more than 9% on the retailer's earnings beat, according to Bloomberg's Billionaires Index.

JCPenney tumbles to an all-time low. Shares cratered more than 27% on Thursday to a record low of $1.75 apiece after the retailer missed Wall Street estimates for the second quarter and slashed its guidance.

Earnings reports trickle out. Deere reports ahead of the opening bell.

US economic data is light. University of Michigan consumer confidence will cross the wires at 10 a.m. ET. The US 10-year yield is down 2 basis points at 2.84%.