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Twitter's stock shot up about 6% Wednesday on the rumors.
But according to Sun Trust analyst Robert Peck, it just wouldn't make sense.
"If you look at what Zuckerberg has done historically, it's been very forward thinking," Peck said on CNBC.
Facebook dropped $1 billion on Instagram in 2012, and $19 billion for WhatsApp and $2 billion for Oculus in 2014.
Mark Zuckerberg also reportedly tried to buy Snapchat for $3 billion in 2013, but CEO Evan Spiegel turned him down.
What do all those companies have in common? At the time of their sales, they were all big bets with a lot of growth potential. Instagram was only two years old, WhatsApp's growth had just hopped on a rocketship, and Oculus's promise of virtual reality for everyone is still relatively uncharted territory.
But with Twitter gaining new users at more of a crawl than a sprint, it's a bit harder to see the same growth potential that could spark Zuckerberg's interests.
The company did offer to buy Twitter for about $500 million in stock back in 2013, but those talks fell through. A acquisition would have made much more sense then than it does now.
"Right now with a company in turnaround mode," Peck says of Twitter, "It wouldn't really fit the bill."