How Alibaba IPO makes Facebook a buy: Cramer

Investors might "like" Facebook (FB)'s stock-but when's a good time to buy shares?

Alibaba Group, the Hangzhou, China-based Internet retailer behind what could be the biggest initial public offering for a technology firm in the United States, could provide that opportunity, CNBC's Jim Cramer said Thursday.

Read More As Alibaba readies for IPO, Cramer offers caution

"You're gonna get a chance to buy it, I think, when the big mutual funds sell stocks in order to take in Alibaba. They can't just all sell their Amazon (AMZN). They're going to sell other stocks that are growth stocks," Cramer said on "Squawk on the Street."

"I would not buy more here," he said. "I would wait until you get some selling off what I see to be the deluge that's going to come from Alibaba."

As the world's No. 1 online social network, Facebook has the kind of reach that makes advertisers salivate, Cramer said.

"Remember when we used to say, 'Half the people read the advertising. We just don't know which half?'" Cramer said. "Well, 100 percent of people read the advertising. We know exactly who they are: the people on Facebook."

-By CNBC's Drew Sandholm

DISCLOSURE: When this story was published, Cramer's charitable trust owned Facebook. It did not, however, own Amazon.com.