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What you need to know today

Another week of losses
U.S. stocks were mixed Friday, but movement was mostly marginal. Still, major indexes ended the week in the red. European markets traded lower too. The U.K.'s FTSE 100 lost 0.65% as data showed the country's retail sales in July fell 1.2% month on month, more than two times the 0.5% decline forecast and down from a 0.6% expansion in June.

A 'perfect storm' battering markets
Surging global bond yields, a slumping Chinese economy amid a worsening property sector crisis, the possibility of higher interest rates in the U.S. — those factors combined to create "the perfect storm" that battered stock markets last week, analysts say. It wasn't just U.S. markets that fell — Hong Kong's Hang Seng Index closed in bear market territory Friday.

Blasting off bitcoin holdings
Bitcoin dropped to $26,212 as of publication time. Compared with its price a week earlier, that's a dramatic fall of around 11%, its worst since November. The sell-off appears to be prompted by a report that Elon Musk's SpaceX had sold its bitcoin holdings in 2021. Despite the plunge, bitcoin is still up about 57% this year.

X-ing the block function
Users of X, formerly known as Twitter, might lose the ability to block other users, according to a post by X owner Elon Musk. "Block is going to be deleted as a 'feature', except for DMs," Musk wrote Friday. Critics of the decision argue that the block function protects users from hateful content and harassment.

[PRO] 'Three' things to look out for
The week ahead will "revolve around three things," said Infrastructure Capital Management CEO Jay Hatfield. "Nvidia's earnings, Nvidia's earnings and, to a lesser degree, Jackson Hole." CNBC Pro's Sarah Min lays out what analysts expect from the chipmaker's highly anticipated report, and how Federal Reserve Chair Jerome Powell's speech could move markets.

The bottom line

The S&P 500 started its precipitous plunge around mid-August last year, sunk by the deadweight of technology stocks. And here we are a year later, experiencing an unwelcome sense of déjà vu.

Technology stocks couldn't stop tumbling for the week. With its 1.7% loss Friday, Tesla, in particular, marked its sixth straight session of losses — its longest down streak this year. It's a jarring echo of the electric vehicle company's horrible December.

Another victim of the week's sell-off was Cathie Wood's ARK Innovation ETF. It lost around 4.7% last week for its third consecutive weekly loss. Like Tesla, the tech-heavy fund hasn't seen such sustained losses since December last year.

All that meant major indexes had a bad week. On a weekly basis, the S&P 500 was 2.1% lower and the Nasdaq Composite slipped 2.6%. It was the third consecutive losing week for both indexes, the first since February for S&P and since December for the Nasdaq. The Dow Jones Industrial Average shed 2.2% for its worst week since March.

What does this mean? Are we stuck in a new market paradigm, where volatility rules U.S. stocks?

Quite possibly, according to Grantham Mayo Van Otterloo, the investment firm founded by Jeremy Grantham. GMO thinks no major asset class will surpass the long-term average U.S. stock market return of 6.5% over the next seven years.

GMO thinks U.S. large-capitalization stocks, in particular, will be the worst-performing asset class, with a likely real return of -3%, followed by U.S. small-cap stocks at -2.4%.

Still, there's a silver lining: Emerging market value stocks will return 6% per year after inflation, in local currency, through 2030. Investors may want to take heed of this advice to diversify.

Correction: An earlier version of this report mischaracterized GMO's data.