(Bloomberg) -- Chewy Inc. and Petco Health and Wellness Co. shares soared and quickly faded on Thursday after Keith Gill — known online as “Roaring Kitty” — posted a cartoon image of a dog on X.

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Chewy, which ships supplies like pet food directly to customers, quickly lurched higher by as much as 34%, the most intraday since June 2019. Petco jumped as much as 12%, with both stocks triggering volatility halts along the way. The rallies were short-lived: Chewy closed down 0.3%, and Petco eked out a gain of 0.3%.

Stocks don’t typically shoot up like that unless there’s “normal news” like a takeover, upgrade or buyback announcement, said Steve Sosnick, chief strategist at Interactive Brokers LLC. However, in this case, “it’s a picture of a dog” that’s driving the moves, he added.

Gill rose to prominence in 2021 as he rallied retail investors around video game store GameStop Corp. under the online moniker “Roaring Kitty.” His social media accounts had gone dormant before he re-emerged this year, posting vague images and videos and reigniting interest in the so-called meme stocks. He disclosed a stake worth hundreds of millions of dollars in GameStop in a post on Reddit, and went on to hold a livestream to discuss the stock earlier this month.

His Thursday post of the dog was not accompanied by any text, similar to the initial item he posted in May of a man leaning forward in his seat while holding a video game controller. That image sent GameStop shares soaring 74% in one session.

Gill’s return set off a volatile period for GameStop and other meme stocks, which both the video game retailer led by investor Ryan Cohen — a co-founder of Chewy — and movie-theater chain AMC Entertainment Holdings leveraged to sell shares.

Chewy has attracted outsized options volume in recent sessions, including on Thursday. By the time the stock market closed, the number of calls traded in the firm nearly quadrupled the average over the past month, with volume led by a contract expiring Friday. The call option — which has a strike price of $45 — still needs a 55% rally to be worth something.

Representatives for Petco and Chewy didn’t immediately respond to emailed requests for comment on Thursday’s sudden swings.

--With assistance from Katrina Compoli.

(Updates stock moves for the market close in second paragraph and chart, and options market activity in seventh paragraph.)

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