A retail trader who quadrupled her AMC holdings to half a million dollars is trolling Citadel's Ken Griffin with plane banners and truck ads

• 40-year-old Katherine Larsen isn't backing down on trolling Citadel Securities and Ken Griffin.
• She's bought plane banners and mobile truck ads to "spread awareness," Institutional Investor reported.

One retail trader isn't letting up on her trolling campaign against Citadel Securities and its founder, Ken Griffin.

The trader, 40-year-old Katherine Larsen of Oceanside, California, has bought mobile truck ads, plane banners, and Times Square digital billboards in an effort to elevate views of retail traders who feel they were harmed when Robinhood halted trading of meme stocks like GameStop and AMC, according to a profile from Institutional Investor.

One ad read "Do you believe #Ken Griffin lied?" and another read "#Citadelisnotretail," the report said. On Monday, she tweeted a photo of a plane banner reading "#stillherekenny wewantfairmarkets.org."

The report said Larsen, a bartender at The Kraken bar in Cardiff, California, invested in movie theater chain AMC in January and has since quadrupled her investment to $520,000. On Twitter, she's known as @katstryker111, and her background photo features an ape with green laser eyes - a familiar icon among the retail trader crowd.

Though her investment has been profitable, she's questioned Wall Street practices, like payment-for-order-flow, the Institutional Investor profile said, quoting Larsen as saying she wouldn't "back down" and wants to continue to "spread awareness." In a Twitter message, Larsen confirmed with Insider the report according to the Institutional Investor.

Insider reported in September that a class-action lawsuit alleged market maker Citadel Securities conspired with Robinhood to drive down the price of meme stocks such as GameStop and AMC on January 28 when buying was halted on the trading app.

Citadel Securities has fired back at retail traders on Twitter saying they were spreading "internet conspiracies" and an "absurd story." Ken Griffin last week said the theories were like a bad SNL joke. Citadel Securities declined to comment for the story.

A 45-page report from the US Securities and Exchange Commission debunked some of the theories about the episode in January. Among other findings, it said Citadel Securities and others weren't grabbing up GameStop stock to hedge against call options they were writing, Axios reported.