[6][7] Henry started trading corn and soybean futures to learn the basics of hedging the price risk of holding an inventory of these commodities, whether in storage or out in the field.

After spending a summer in Norway with his first wife, Mai, Henry developed a mechanical trend following method for managing a futures trading account.

When that test proved successful, he founded John W. Henry & Company in 1981,[8] opened a small office across the street from the airport in Irvine, California, and began marketing his management to the largest commodity brokerage firms in America.

In March 2006, Boston magazine estimated Henry's net worth at $1.1 billion, but also reported that his firm had experienced recent difficulties.

In January 2002, Henry sold the Marlins in a multi-franchise deal to Jeffrey Loria, then owner of the Montreal Expos, which is now the Washington Nationals.

[19] In 2001, Henry partnered with Tom Werner, The New York Times Company, and other investors to found New England Sports Ventures (NESV) in a successful bid to buy the Boston Red Sox from Yawkey Trust headed by John Harrington.

[clarification needed][28] The previous owners, Tom Hicks and George N. Gillett, Jr., had become extremely unpopular among Liverpool fans for their failure to deliver on the promise that no debt would be placed onto the club, and the proposal of Liverpool leaving Anfield as disrespectful treatment of its manager and front office[29][30][31] and for their allegedly misleading statements about planned and past investment in players.

[32][33] After losing around £154 million on the pressured sale of their debt-ridden club, Hicks and Gillett announced that they would sue co-owners and creditors for at least $1.6 billion for the "extraordinary swindle" they suffered.

[34][35] On February 26, 2012, Liverpool won the 2012 Football League Cup Final at Wembley Stadium, beating Cardiff City 3–2 on penalties after the game finished 1–1 after 90 minutes and 2–2 after extra time.

[36][37] In July 2012, after successfully persuading Brendan Rodgers to become the new coach,[38] Henry attributed parting company with Dalglish as being unrelated to failing to win the FA Cup or the Suarez case,[39] but a product of the club's poor league performance in the second half of the 2011–12 season.

In 2019 Liverpool reached the Champions League Final for the second consecutive year and won it, beating fellow English club Tottenham Hotspur, 2–0.

[46] Driver Matt Kenseth won the Auto Club 500 at the California Speedway in February 2007 marking Henry's first win as an owner.

In the predawn hours of August 3, 2013, both The Boston Globe and The New York Times carried stories on their web sites reporting that Henry had agreed to purchase the former along with the Telegram & Gazette newspaper of Worcester, Massachusetts, and related New England media properties for $70 million in cash from The New York Times Company, which paid $1.1 billion for The Globe in 1993.

[48] The stories noted that Henry had initially been among a group of partners who had joined in bidding on The Globe properties, but ended up agreeing to acquire them individually.

[49] In 2014, Henry sold the Worcester Telegram & Gazette to Halifax Media Group, which had previously purchased 16 former New York Times Company newspapers in 2011.

[52] Henry was briefly portrayed by Arliss Howard in the 2011 film Moneyball, which follows Oakland Athletics general manager Billy Beane and his quest to build a winning team in 2002.