Reading up on it was easier than I thought it would be.

Overstock.com - Naked short selling campaign - Wikipedia

The company has received attention stemming from CEO Patrick Byrne's battle against alleged naked short selling of his company's shares. Beginning in 2005, Byrne has contended that a number of companies, including Overstock.com, have been the targets of this practice, which involves selling a stock short but without the usual step of initially borrowing or locating the shares. Byrne alleges that the practice circumvents safeguards of conventional shorting, and has been used in large schemes devised to profit from driving down the prices of companies' shares, in many cases leading to these companies' failure. With Overstock, Byrne contends that the company's longstanding appearance on the Regulation SHO Threshold Security list, an SEC-mandated list showing companies with a high number of "fails to deliver," along with high trading volumes that sometimes surpass total quantity of the company's stock, establish that it has been targeted by this practice.^[29]

Byrne's campaign has been controversial, including criticism in the financial press that Byrne is seeking to divert attention from Overstock's share price declines and failure to turn a profit.^[30] New York Times columnist Joseph Nocera has said in 2006 that, "Except for a few fellow-traveling Web sites, where Mr. Byrne is viewed as a heroic figure, most people who understand the issue or have looked into it think it's pretty bogus."^[31] Others have suggested that the problem is real, but that the SEC acts to prevent it and that it does not happen on any scale such as Byrne suggests. SEC Chairman Christopher Cox called abusive naked short selling “a fraud that the commission is bound to prevent and to punish.”^[32]