Chinese drone maker DJI, the world’s largest maker of recreational small UASs, lost $150 million last year due to a wide-sweeping internal financial fraud in which some employees inflated the cost of parts and materials and diverted the proceeds for personal financial gain, according to the company. In a statement issued this morning, DJI said it “took swift action to address this issue, dismissed a number of employees who violated company policies, and contacted law enforcement officials. We continue to investigate the situation and are cooperating fully with law enforcement’s investigation.”

The company further said that it is “taking steps to strengthen internal controls and have established new channels for employees to submit confidential and anonymous reports relating to any violations of the company’s workplace conduct policies.” This fraud investigation to date has resulted in the termination of 29 employees, the referral of 16 for criminal prosecution, and could potentially involve more.

Privately held DJI was founded in 2006 by Frank Wang who had received an $18,000 grant from the Hong Kong University of Science and Technology for drone research in 2003. It has 14,000 employees, commands 74 percent of the light drone market, had $2.9 billion in sales in 2017, and has an estimated valuation of $15 billion.

The company is widely expected to issue an initial public offering (IPO) of its stock later this year. Various quarters have raised security concerns about DJI products. In May, the U.S. Department of Defense banned the purchase of consumer drones from a variety of manufacturers including DJI and in November various media outlets reported that DJI drones were vulnerable to data/photo hacking via a vulnerability in its cloud infrastructure, a problem DJI said it has patched.