Any particular type of business?
Media. He's just bought Newsweek, the US weekly news magazine, for the princely sum of $1 (60p).
Wow, that's cheaper than a copy of the magazine.
To be fair, Mr Harman's full outlay may be a little larger – the magazine was put up for sale by the Washington Post Company in May because it couldn't stop losing money. The magazine may have "national treasure" status but it has lost $44m over the past three years.
Well, thank goodness it has a new owner to keep it going long-term.
Hmmm. The good news is Mr Harman says he is "in no hurry" to make a return on his investment. On the downside, he's 91. He looks well, but still.
Why has he bought it?
Well, Mr Harman does have a long record of generous philanthropy – in the US magazine market, where advertising has not recovered from the recession and readers have migrated online, that's the sort of proprietor needed. He's also a patron of the arts and says he believes in the Newsweek mission.
Does he have deep pockets?
He's certainly well off, having made his money from the audio company, Harman/Kardon, which bears his name. Stereo aficionados will tell you that Mr Harman and his partner, Bernard Kardon, effectively invented the home music system by coming up with the first integrated audio receiver.
What else has he done?
Quite a lot, actually. In the 1960s he taught African-American school children in Virginia, when the state closed its education establishments after being ordered to desegregate them. He also taught at Friends' World, an experimental Quaker college on Long Island.
He sounds quite the liberal?
Did I mention that his policy of giving staff freedom to set their own working hours and to contribute ideas to the company led to a spell as President Jimmy Carter's deputy secretary of commerce?