Even bankers advising SeraCare were skeptical of Shkreli's fund, saying "they understood it to be a relatively small fund that likely would be unable to complete a transaction without third-party financing," according to SeraCare's own filings.
Publicly available stock-trading information also suggests that, at nearly the same time Shkreli disclosed to regulators that he owned 5.17 percent of the company, he may have amassed an equally large short position. That strategy, known in Wall Street parlance as "boxing," is common in trading circles but is rarely, if ever used, when trying to buy a company, experts say. That's because Shkreli would have been left with no significant net ownership stake in the company had the deal gone through.
Trading data examined by CNBC show that while Shkreli publicly disclosed ownership of more than 950,000 shares in SeraCare in July 2011, the "short-interest," or number of shares investors were betting against the company, dramatically spiked virtually overnight to nearly the same number of shares. That spike came after short interest in Seracare had hovered at just around 70,000 shares for weeks prior.
The SeraCare shareholder told CNBC on Friday that he noticed the unusual activity in the stock, believed it was Shkreli responsible for the large short position, and doubted that Shkreli really wanted to buy the company.