FILE PHOTO: The logo of U.S. conglomerate General Electric is pictured at the company's site of its energy branch in Belfort, France, February 5, 2019. REUTERS/Vincent Kessler/File Photo

NEW YORK (Reuters) - Betting against General Electric Co GE.N stock has increased in the last week as the stock has fallen following a report by fraud investigator Harry Markopolos that questioned the conglomerate's accounting, financial analytics firm S3 Partners said on Tuesday.

Short sales, or bets that GE’s stock price will fall, rose 13.5% to $14.3 million in the last week and 20.7% to $20.6 million in the last month, Ihor Dusaniwsky, managing director of predictive analytics at New York-based S3 Partners, told Reuters.

GE stock closed down 3.3% at $8.38 on Tuesday, and is down about 7 percent since Markopolos’s report came out last Thursday.

S3 Partners uses an algorithm to calculate daily short interest based on market data and insights from $2 trillion in assets the firm has under advisement, Dusaniwsky said.

The firm estimates that short-sellers’ unrealized profits have climbed 7.3% in the last week and 18.6% in the last month. The data also suggest more short-sellers have bet against GE’s stock and that no major investor has closed, or covered, its short position, the firm said.

“When short sellers see something like this they tend to jump in as a pack,” Dusaniwsky said. “We’ve not seen any covering in size.”

Markopolos, who blew the whistle on Bernard Madoff’s Ponzi scheme, said on Thursday GE was concealing deep financial problems, prompting a sharp rebuke from GE’s new CEO. He said he was working with an undisclosed hedge fund to profit from short selling.

Concerns raised by the report were echoed on Tuesday by Fitch Ratings, which ranked GE near the top of risky insurers.

GE stepped up its defense of its insurance accounting on Monday.