Martin Shkreli, famously known as 'Pharma Bro,' has returned to the public eye, taking short positions against companies and actively using social media to share his investment views. He recently announced a short position against Opendoor Technologies Inc. (NASDAQ: OPEN) at $9.36, promising to conduct a public due diligence campaign that includes speaking with former employees, customers, and competitors. This move follows his earlier bearish stance on Opendoor, which he dubbed an "obvious short," comparing it to his successful short call against Newegg Commerce Inc. (NASDAQ: NEGG).

Shkreli's re-emergence comes as Opendoor's stock, often labeled a "meme stock," had seen a dramatic rise of over 1,000% from its 52-week lows. His bearish bet aligns him with other prominent short-sellers like Andrew Left of Citron Research, who called Opendoor "a science project in how to burn money." Shkreli's public due diligence is expected to intensify the volatile battle between retail investors, who have driven Opendoor's stock up by approximately 1,500% since July following a bullish call from hedge fund founder Eric Jackson, and institutional bears.

Beyond Opendoor, Shkreli has also taken a short position in aTyr Pharma (ATYR) shares, alleging that the company's lead drug, efzofitimod, is ineffective in treating systemic sclerosis-related interstitial lung disease (SSc-ILD). He criticized the drug's Phase 2 data and preclinical data, arguing its mechanism of action lacks scientific rationale, and predicted an 80% crash for aTyr shares within six weeks. Despite his claims, Wall Street analysts largely maintain a "Strong Buy" consensus rating on ATYR, with a mean price target around $20, indicating a potential upside of approximately 300%.

Shkreli, who previously served time for securities fraud and was barred from the pharma industry for life, has been actively building an audience on social media for his investment advice since his release. He is also involved with Q/C Technologies Inc., a micro-cap firm where he is a strategic advisor, focusing on photonic computing as a potential disruptor to Nvidia's GPU dominance in AI hardware. This diversified approach signals his intent to not only bet against companies but also build public cases against them and engage in new technological ventures.