Dell, who has a fortune of $15.3bn, was the mystery investor for whom Stealth completed a $33m private placement earlier this month, SEC filings show.

His investment fund MSD Capital controls 3,494,636 shares in the shipowner, giving it a 9.8% slice, documents reveal.

StealthGas chief executive Harry Vafias confirmed the purchase in a deal brokered by Global Hunter Securities.

"We are extremely excited and proud that one of the United States' major billionaires is investing with us," Vafias said.

Rich company

Dell joins the ranks of the wealthiest shipping investors. His $15.3bn fortune placed him at number 49 on the Forbes Rich List last year.

This put him well ahead of John Fredriksen, with $11.5bn in 87th, spot and private equity magnate Wilbur Ross, who was ranked 554th with $2.6bn.

George Soros, who boasts Scorpio Bulkers among his many investments, had $19.2bn and was ranked 30th by Forbes.

StealthGas chief executive Harry Vafias at the Nasdaq stock exchange
 

MSD was set up in 1998 exclusively to manage capital for Dell and his family. In addition to stocks and shares, it owns real estate and is involved in private equity transactions.

Vafias told TradeWinds a couple of weeks ago the investor, who he declined to identify at that stage, had been pursuing stock in the company for several months.

Strong early signs

Dell’s StealthGas investment is looking good. His shares were worth $35.47m at the close of trading on the Nasdaq last night.

LPG is one of shipping’s hot sectors right now. “LPG has been in vogue since the second quarter of 2013,” Vafias said a couple of weeks ago.

Reporting fourth quarter 2013 results last week Vafias told investors StealthGas would continue to focus on expanding its fleet of LPG carriers.

After taking delivery of 17 newbuildings by the end of next year the company will control some 25% of the tonnage in its core market, Vafias said.

Other major StealthGas shareholders include, Massachusetts Financial Services Company with 5.2% and Royce & Associates with 4.16%.

Vafias and his family control slightly more than 20% of the stock.