Citron has launched 51 investigative reports against S&P 500 companies between 2009 and 2015, as well as several Chinese companies, citing allegations of pyramid schemes, ineffective products and accounting or business frauds. Despite being sued by multiple companies for the reports he has released, Left claims he has never lost a case in the United States.
Left was born in a Detroit suburb and later moved with his family to Coral Springs, Florida. He attended Coral Springs High School where he was a member of the debate team and president of the Jewish youth group. He attended Northeastern University in 1993.
Left's first job was with Universal Commodity Corp, a high-pressure commodities brokerage firm that hired salespeople to make cold calls and push "questionable investments." Left quit in March 1994, after 9 months with the company. When the National Futures Association sanctioned the firm in December 1998, Left, along with every other former employee, was sanctioned for three years along with being required to take an ethics-training course as part of the probe into the firm for making false statements to sell commodity futures contracts. The National Futures Association stated Mr. Left “made false and misleading statements to cheat, defraud or deceive a customer in violation of NFA compliance rules.”
Left became active in short selling by the age of 24. He has cited his experience with Universal Commodity Corp as the reason he started short selling stocks promoted by boiler-room scams. When the boiler rooms eventually went out of business, Left started shorting stocks from bulletin-board scams, in which people would send out email blasts saying, "Buy this stock now or you'll miss out."
In April 1999, Left became president and CEO of Detour Media. He was named director of the company in November 1999. In 2002, his then employer Detour Media sued Left and prevailed on a $25,000 default judgment against him.
Left switched to shorting the stocks full-time, using his own research to publish free reports on firms he feels are overvalued or engaged in fraud. In 2001, he founded StockLemon.com, now known as Citron Research. According to Left, he has made profits every year since he started short selling. He was a keynote speaker at the 2017 Harvard Business School Investment Conference.
Left initially started StockLemon.com in 2001 as a self-published blog containing reports on controversial companies. He rebranded the site as Citron Research in 2007. Left researches and short sells companies he believes to be engaged in fraud, have been suspiciously promoted, or have been mistakenly overpriced by the stock market.
According to a Wall Street Journal analysis of 111 Citron short-sale reports spanning from 2001 to 2014, there was an average share-price decline of 42 percent in the year after Left's report was released. Of those shares, 90 were lower one year later while 21 gained, according to data from S&P Capital IQ.
GTX Global Corp. sued Left for defamation after a 2005 article he published through Citron about GTX Global. In 2007, the case was dismissed under California's anti-SLAPP statues which cover writings about publicly traded companies as matters of public interest.
In 2008, Left released a report in which he concluded that Home Solutions was not transparent about the company's relationship with American Renaissance. Home Solutions had loaned money to American Renaissance before the "partnership" was disclosed publicly. As a result of Left's research, Home Solutions’ stock plummeted. Starting in 2012, Left published multiple reports about Questcor Pharmaceuticals centered around incorrect labeling of the drug Acthar's ingredients. When Questcor was acquired by Mallinckrodt, Left criticized the new company for continued misconduct. Several of Left's reports have become highly publicized, including a 2012 report on the legality of operations by Nu Skin Enterprises, and a 2015 report on Valeant Pharmaceuticals bringing attention to inflated sales.
Left's 2015 report on Valeant Pharmaceuticals accused the company of channel stuffing and using sham transactions to inflate drug sales. Left's initial report focused on an investigation launched by Senator Bernie Sanders and Representative Elijah Cummings that examined Valeant's business model of massively spiking the prices of drugs to which it had acquired marketing rights. Left followed up with a report focused on pharmaceutical distributor Philidor RX. Left called for the US Securities and Exchange Commission to investigate the issue and referred to the company as the "Pharmaceutical Enron". As a result of the report, Valeant shares dropped after a five-year peak, eventually falling more than 90 percent from its peak in August 2015, and announced the resignation of longtime CEO Michael Pearson the following March.
Citron Research has published reports on 18 Chinese companies, 16 of which experienced a drop in stock prices, with 15 of them experiencing drops of over 70%. This has caused a collective of Chinese business leaders, including Qihoo 360 CEO Zhou Hongyi (a company that has been targeted by Left), to launch a site called CitronFraud.com (no longer operating). Left sent a legal notice to the 60 Chinese executives involved, seeking an apology, and told Tech In Asia that he is consulting with lawyers and considering legal action in response. Qihoo 360 has also threatened to take legal action against Citron, as well as former Google China chief Kai-Fu Lee, now the chairman and CEO of Innovation Works.
In 2011, Left released a report through Citron about Longtop Financial, a financial software house based out of China, accusing it of defrauding shareholdings, over-reporting revenues, and lacking transparency in the company's acquisition process. The report pointed out Longtop's outsized margins and unexplained stock grants and pointed out Longtop's relationship with China's largest banks. The company was later issued a Wells Notice of impending criminal charges from the SEC.
In 2016, the Hong Kong Securities and Futures Commission accused Left of spreading false and misleading information about Evergrande Real Estate Group Ltd. The trial marks the first legal action of the Securities and Futures Commission against a short seller with ramifications for free speech, according to the judge. Left had been researching Evergrande since 2012 when he received papers from an anonymous whistleblower, and claimed they were insolvent and the chairman's credentials were false. Later in 2016 A Hong Kong tribunal banned Andrew Left from trading for five years after publishing “false and/or misleading” claims about China Evergrande Group. Left was ordered to repay HK$1.6 million in trading profits, pay about HK$4 million in legal expenses, and face criminal prosecution if he breaks Hong Kong rules again.