We have the answer: It’s a Swatch, a simple plastic timepiece that retails in the ballpark of $100. In fact, the executive has several of them—including a black one for formal events.

Public-facing figures like Schwarzman and Blankfein may be expected to dress without excessive bling. And yet, as Google attests, it’s curious to see a plastic bangle on some of American business’s most powerful men. The list of power players who sport Swatches goes on: Tony Blair has one, as does French president Francois Hollande. U.K. hedge fund trader Chris Hohn has had a black one for years. AllianceBernstein CEO Peter Kraus is a fan of the brand. Even the boss of luxury watch maker PatekPhillipe reportedly wears one while skiing.

In a statement to Fortune, Switzerland’s Swatch Group didn’t have much to say about why politicians and executives might want to wear the budget accessory. The company’s Swiss roots and artistic designs may play a role, a spokeswoman said. When the Swatch was introduced as an alternative to Asian mass production in the 1980s, it was credited with helping to save the Swiss watchmaking industry. Ultimately, though, the watch brand’s patronage among the high and mighty is a bit of a mystery. “We assume that politicians have their reasons for wearing our watches,” the spokeswoman wrote, “but we don’t know what those reasons are.”

Plastic watches aren’t new in the halls of power. Even before the Great Recession made modesty a must, Timex Ironman watches had become a mainstay for leaders who either lack pretension, or have enough pretense to want to appear that way. Bill Clinton, for example, has worn an Ironman. The previous three Goldman chiefs also wore them. Hank Paulson’s was a gift from Stephen Friedman, says Goldman chronicler William Cohan. Jon Corzine, too, has been known to sport the look—which is on offer for about $40 at Target.

Why plastic? Putting aside the convenience of battery power, there are plenty of reasons not to go digital. The watch is the ultimate male accessory. In a world of subtle variations of dark suits and understated shoes, the wrist may very well be the one area in which is it socially permissible for a man to be sartorially dazzling (okay, yes, perhaps the tie as well). At the Baselworld tradeshow, the horological spectacle that wrapped up earlier this year, the watches on display did much more than tell time. Want to look at 12 different time zones in a single glance? No problem. One that tracks a dozen of your friend’s birthdays? Coming right up. How about a hand-finished model encased in rose gold? Only $510,900.

Increasingly, though, minimalism is in. Even at Baselworld, classic watches were resurgent. Collectors have become less concerned with ostentation than with authenticity. Comfort is also a growing priority. Pick your trend: “soft dressing,” “slobcore,” “athleisure”—today’s buzzwords speak to a fashion landscape that doesn’t have room for flashy Rolexes. The Gap is doubling down on yoga pants as the luxury loungewear category explodes. And more than one designer put sweatpants on the runway at this year’s Fashion Week.

Yet it’s more than the vagaries of style, or even simple reverse-snobbery, that has prodded executives to buy Swatches. At a big bank, a plastic watch is as intimidating in its own way as a diamond-studded PatekPhillipe. It signifies a passion for function and disdain for form. Goldman has long been known for its understatement when it comes to dress. A plastic watch exudes that characteristic aversion to flashiness, commitment to modesty, and, in a way, the maniacal work ethic endemic to finance.

That’s because Swatches—unlike, say, VacheronConstantins—are extremely practical. You can work out in them. You can do an Ironman. (Blankfein is a swimmer, and the plastic Swatch dries easily.) Plus, unlike their mechanical counterparts, most cheap watches keep nearly perfect time.

The only thing more practical? Maybe a phone. But even Apple, which has played a leading role in the watch’s wardrobe displacement, clearly sees the merits of a wearable clock. The iWatch has been rumored for years, and we can only speculate about the myriad features it will offer. Luckily for Swatch, some people still just want to know the time.