Amazon CEO Jeff Bezos GettyImages/Alex Wong Amazon CEO Jeff Bezos wished president-elect Donald Trump success moving forward, and congratulated him on his election win, in a tweet on Thursday.

"Congratulations to @realDonaldTrump," Bezos wrote. "I for one give him my most open mind and wish him great success in his service to the country."

This tweet is quite a reversal of attitude for Bezos, and comes on a day when Amazon's stock tanked by more than 4% (along with other tech stocks).

During Trump's campaign, Bezos, who owns The Washington Post, called Trump out for his accusations of mainstream media bias. Bezos said Trump was "eroding our democracy," and suggested that Trump take a trip to space instead. Not exactly the "open mind" Bezos expressed in his tweet.

On the other side, Trump has often criticized Bezos and Amazon.

"I have respect for Jeff Bezos, but he bought The Washington Post to have political influence, and I gotta tell you, we have a different country than we used to have," Trump said during his campaign. "He owns Amazon. He wants political influence so that Amazon will benefit from it. That's not right. And believe me, if I become president, oh, do they have problems. They're going to have such problems."

It seems that Bezos, however, wants to start the presidency off on a note of unity instead of bickering. We'll have to see if Trump feels the same way.

There are many ways a Trump administration could give Amazon a headache — from taxes to anti-trust. See my colleague Eugene Kim's article on all the ways Trump's presidency might affect Amazon.

Investors might be sensing the risk. As previously noted, Amazon stock was down over 4% on Thursday.

Here is the tweet from Bezos:

Previous reporting by Eugene Kim.