J2 Global Inc.’s stock quickly fell nearly 20 percent today to $56.90 a share after a short seller released a report that accused the company of hiding lackluster performance within its financial filings.

Andrew Left of Citron Research claims that J2 Global Inc.’s cloud and media businesses have been underperforming and the company has been covering that up in its financial filings. Left also claimed that J2’s e-fax business is vulnerable to competition due to expiring patents and it is at risk of declining sales because fewer customers use fax communications.

J2 Global of Hollywood has consolidated the e-fax industry and cloud backup storage industries over the last past decade through more than 127 acquisitions of small competitors. Left argued that those rollups aren’t performing as well as J2 Global claims.

“The most important point is, while having a string of acquisitions over six years and spending over $1 billion they have a little more than $20 million in EBIT,” he said. “They are doing a lot of crummy acquisitions. They’ve acquired over 100 companies. It’s like buying a bag of peanuts one peanut at a time.”

In contrast to Left’s report, analysts have been very optimistic on J2’s prospects and financial results.

“Operationally, they run a very tight ship,” Gregory Burns, an analyst with Sidoti & Co. of New York said to the Business Journal last month. “They are hyperfocused on margins, profitability and cash flow.”

Technology reporter Garrett Reim can be reached at [email protected]. Follow him on Twitter @garrettreim for the latest in L.A. tech news.