Yahoo stock looked like a buy on its quarterly earnings report and its stake in Alibaba, Ironfire Capital founder Eric Jackson said Tuesday.

"The core business is really accounting for only 15 percent of the stock price," he said. "Everybody focuses on the core business like it's so important."

Yahoo posted earnings of 34 cents a share, edging past estimates for 33 cents a share, while revenue was in line with forecasts at $1.08 billion, excluding traffic-acquisition costs.

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On CNBC's "Fast Money," Jackson said that its stake in the Asian online marketplace company, headed toward an initial public offering, was a huge plus for Yahoo.

"This is all Alibaba and the results in this report, which were for Q2, were fantastic," he said. "They did over $1.7 billion in the quarter. They did a similar amount of revenue and net income to Facebook. I think they're going to do, easy, $7 billion in revenue this year.

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"And if you apply a Facebook-like 20-times price-to-sales multiple to that, you get an Alibaba that's worth $140 billion, not $100 billion."

Jackson said that he saw plenty of buyers lining up for Yahoo.

"I think a lot of institutions will be buying tomorrow," he said. "They're going to see that the results for Alibaba were continuing to be strong, and they want to own this thing for the next little while."

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Yahoo closed at $33.38 per share, down 1.82 percent, before gaining in after-market trading.

—By CNBC's Bruno J. Navarro. Follow him on Twitter @Bruno_J_Navarro.