Organovo Holdings Inc (NYSE:ONVO) has become a major battleground stock since Citron Research released a scathing short thesis on the company in January. Now Bloomberg Brief reports that another prominent short-seller has echoed the concerns raised by Citron.

Whitney Tilson K12 Questcor Pharmaceuticals QCOR
Courtesy of Kase Capital

Tilson to present on Organovo tomorrow

According to the Bloomberg Brief, a copy of which was reviewed by ValueWalk, Tilson has put together a presentation about Organovo Holdings Inc (NYSE:ONVO) and another recent short position of his—Lumber Liquidators Holdings Inc (NYSE:LL). The Kase Capital managing partner will be giving the presentation tomorrow at the Value Investing Congress Workshop, which will be held in Las Vegas.

Shares of Organovo Holdings Inc (NYSE:ONVO) have more than doubled over the last year as investors excitedly consider the possibility that the company might one day be able to print human organs. Shares of Lumber Liquidators Holdings Inc (NYSE:LL) have risen 36% in the same time frame.

Tilson also shorts 3D Systems

Whitney Tilson is also short another 3D printing company—four others, in fact. In his letter to investors dated February 6, 2014, TIlson said he was short five different stocks in the 3D printing sector and that the biggest one is 3D Systems Corporation (NYSE:DDD). He called the February “blowup” of the company’s stock “the beginning of the end for the 3D printing bubble.”

He said at that time that he wasn’t “the slightest bit inclined” to cover any of his short positions on 3D printing companies. In fact, he also said he shorted 3D Systems Corporation (NYSE:DDD) “a bit more” after “the entirely predictable” analyst rush to reiterate their Buy ratings.

The investor has based his shorts of major 3D printing companies like 3D Systems Corporation (NYSE:DDD) and Organovo Holdings Inc (NYSE:ONVO) on his view that the valuations of the stocks in the industry aren’t real. He notes that 3D printing itself is real but believes that investors are giving the companies multiples which are too high.