STORY: U.S. stocks lost ground on Monday as investors braced for a week loaded with crucial economic data, including a key reading on inflation, and the unofficial kickoff to second-quarter earnings season.

William Rhind is founder & CEO at GraniteShares.

"We'll get CPI numbers again on Wednesday this week. So that's another thing that the market is assessing. Expectations are that the inflation number will be high again. [FLASH] And so people are looking for indications that inflation might start to cool. The other thing is that really you could argue that the performance of the stock market so far to date has been around expectations around future earnings. Less about the actual numbers themselves. [FLASH] I think really what's key is the commentary from the CEOs around what they expect the business environment to be like going forward."

Results from big banks, including JPMorgan, Citigroup, and Wells Fargo - shares of which all fell Monday - are expected to launch the second-quarter reporting season later this week.

The Dow fell half of a percent. The S&P 500 lost more than a percent, while the tech-heavy Nasdaq ended down two and a quarter percent, pulled down by megacap growth stocks, including Apple, Amazon and Google-parent Alphabet.

Twitter shares tumbled more than 11% in the wake of Elon Musk saying he intended to terminate his deal to buy the social media company.

And shares of Musk's Tesla fell 6.5%, as some market participants saw future litigation with Twitter as a potential distraction amid growing worries about the economy and mounting competition from rivals.