What happened

Apple (AAPL 0.45%) stock tumbled 4% through 2 p.m. ET on Tuesday, knocking the tech titan below $2 trillion in market capitalization for the first time since 2021, and putting Apple stock a full one-third below the $3 trillion market cap it hit a year ago.

And yes, you can blame investment bank BNP Paribas Exane for that -- but only in part.

So what

As its first stock action of the new year, BNP downgraded Apple stock from outperform to neutral this morning, and slashed its price target on the tech giant by 22%, to just $140 a share.

It's not yet known how many total gadgets Apple produced in 2022. But citing supply chain issues in China, BNP said Apple is likely to ship no more than 224 million iPhones in 2023, down 7% from 2021, reports StreetInsider. Mac and iPad shipments are also expected to fall this year, and earnings could decline by as much as 6% (in which case, they'd also miss Wall Street estimates, which call for flat earnings this year).  

BNP's downgrade is certainly weighing on Apple stock today, but it's worth pointing out that BNP may only be reacting to other news that necessitated the downgrade. Specifically, Nikkei Asia has reported that Apple is warning its suppliers that it sees weak demand for its products this year, so it won't be ordering as many components for its devices.  

Now what

Granted, when you consider that COVID-19-related supply disruptions in China were already making it difficult for Apple to build all the devices it wanted to, the fact that Apple is affirmatively ordering fewer parts right now might not be as big a deal. The demand problem may be canceling out the supply problem for Apple!

That being said, whatever the reason for the slower sales, this is not a development calculated to make Apple investors happy. Even at a current valuation of 18.5 times free cash flow -- which sounds kind of cheap for a stock like Apple -- analysts are forecasting no more than single-digit earnings growth for the company over the next four straight years. With at least one high-profile analyst now warning that earnings could actually shrink, rather than grow, in the current year, it's no wonder that investors might be starting to worry that Apple stock is actually overpriced.