How Tim Cook reversed Apple's plummeting stock price

Apple's CEO emailed CNBC's Jim Cramer to reassure investors that all is well. Jordan Golson explains.

Yesterday was a historic day for the world's financial markets. The Dow Jones Industrial Index took a hammering, dropping 3.57%. It was an improvement over the early minutes of the trading day, but still a tremendous whack.

An hour after the trading day began, the DJIA began gaining back some of its losses, partially thanks to a single email sent yesterday morning.

It wasn't just any email, however—it was a missive from Apple CEO Tim Cook to influential CNBC host Jim Cramer, saying that all was well for Apple in China (where much of the current market uncertainty is centered).

"As you know, we don't give mid-quarter updates and we rarely comment on moves in Apple stock. But I know your question is on the minds of many investors.

"I get updates on our performance in China every day, including this morning, and I can tell you that we have continued to experience strong growth for our business in China through July and August."

After CNBC reported the contents of the email, Apple's stock shot upwards after being down an astounding 10% on the day, rising temporarily into positive territory and finally finishing the day down 2.5% at $103.12.

It's possible that Cook's email may have violated SEC rules, because it gives a look into Apple's performance in the middle of a quarter, well ahead of an expected earnings call in mid-October.

Cook could face an investigation or at least an inquiry into the email exchange with Cramer, but it's also possible that Cook will get a pass because of the extraordinary market activity yesterday. Cook's email had the effect of "righting the ship" somewhat and bringing some calm into the markets. The SEC fair disclosure rules require companies to share material information with all investors simultaneously, something that can even be done via Twitter.

Apple is one of the stocks in the influential and closely-watched Dow Jones Industrial Average, and it's positive spike had an effect on the rest of the market as well. It also likely helped reassure investors about the state of the economy in China, a massively important market for Apple and where much of its recent growth has occurred.

Cook noted to Cramer that he believes China "represents an unprecedented opportunity over the long term" for the company because of low LTE (high speed cell service) penetration and a rapidly growing middle class.

Still, it reiterates that Apple is special. It's so huge and so influential that a single email from its notoriously secretive CEO can, perhaps, change the fortunes of the entire US stock market—for a few hours, anyway.