Billionaire investor Carl Icahn acquired a new 9.7 percent stake in business services provider Conduent Inc. in the first quarter and sold out of pharmaceutical giant Allergan Plc. and speech technology group Nuance Communications Inc.

Icahn raised his stake in truck-maker Navistar International Corp., according to a regulatory filing Monday. The changes also reflected the takeover of Federal-Mogul Holdings by his publicly traded company Icahn Enterprises LP.

Icahn increased his stake in Herbalife Ltd., which he has been acquiring against the backdrop of a public feud with hedge fund manager Bill Ackman. Pershing Square Capital Management, run by billionaire Ackman, has a short position in the nutrition supplements distributor.

President Donald Trump named Icahn as a special adviser in December. The outspoken New York investor, who endorsed Trump’s candidacy in September 2015, has said he will be “rallying against overregulation” and giving his opinions in that role.

Icahn rose to fame in the 1980s as a corporate raider has re-branded as an activist investor and shareholder advocate. Worth about $20 billion, according to the Bloomberg Billionaires Index, Icahn primarily invests his own fortune rather than relying on money from outsiders.