“Y-O-F**KING-LO,” the teen wrote, flashing his trading statement. “900 to 55K in 12 days!”

On Reddit, he’s known as “World Chaos,” a Florida high schooler who earlier this year multiplied his money by betting against the S&P 500. His real name is Jeffrey Rozanski, and the 18-year-old’s appetite for risk would make many seasoned market players facepalm.

In one corner of the Internet, though, praise rained down. “You magnificent bastard,” read one reply. “Sailing away on your yacht while the rest of us f**kers who went long are looking for the nearest window.”

That was peak “WallStreetBets,” the Reddit forum where “YOLO” is the war cry, Martin Shkreli is a role model, and irreverent traders trawl for tickets to quick wealth. It has become what one member calls “the beating heart of millennial day traders.”

“It’s tasteless, hilarious and subversive,” said Erik Johnson, a 28-year-old manufacturing worker and forum regular from Boston. “And you definitely need to have a thick skin to partake.”

The latest obsession on WallStreetBets is UWTI US:UWTI, an exchange-traded note that has become a favorite of younger investors — thanks, in part, to the Reddit forum. It is a near-perfect embodiment of the YOLO spirit: Highly volatile, it uses a combination of derivatives and debt to amplify bets on oil, creating opportunities for quick profits.

And, of course, wrenching losses.

Reddit as financial adviser

Reddit, which calls itself the “front page of the Internet,” hosts a collection of discussion boards that operate more like hive mind than social network. Users vet posts through a system of “upvoting” and “downvoting,” and they have proven both dedicated to ideals of free speech and impervious to political correctness.

While fewer than 10% of U.S. adults say they use Reddit, it has become an influential sounding board of super-engaged users, nearly 70% of whom are male, while 56% are between 18 and 29.

In other words, it’s just the kind of place you might expect rowdy young traders to gather in 2016.

A screen capture of the header image on WallStreetBets

Another Reddit forum, or subreddit, called Investing has more members — more than 183,000, compared with about 38,000 “YOLOers,” which WallStreetBets calls its subscribers. (“YOLO,” short for “You Only Live Once,” became a popular term in 2011 after Drake used it in a song.)

But WallStreetBets is lively, engaged and growing. It was in the top 1% of Reddit’s more than 824,000 subreddits in new-subscriber growth over the past 90 days, according to RedditMetrics.com, and its more than 2 million monthly page views represent more traffic than all of the other stock-related subreddits combined.

Jaime Rogozinski, a 34-year-old who has worked in international banking and recently moved to Mexico City to work in finance with early-stage startups, created WallStreetBets after getting “downvoted” for discussing risky bets on the Investing subreddit.

If the Investing subreddit is a mild-mannered financial adviser who advocates diversification and dividend stocks, WallStreetBets personifies a foul-mouthed, risk-taking day trader.

The forums are “kind of like archnemeses,” said Rogozinski.

WallStreetBets also claims a famous alum: “Pharma bro” Shkreli was once a moderator, though he deleted his Reddit account after his social-media accounts were hacked.

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“This subreddit, they love Martin Shkreli,” said Asad Butt, a 25-year-old Pennsylvania trader who posts frequently to WallStreetBets. “He is living their dream. He got rich. He might have lied and cheated along the way, but [on the forum] that’s encouraged.”

Martin Shkreli with lawyer Benjamin Brafman after a hearing of the House Oversight and Government Reform Committee in February. Getty Images

In 2015, Shkreli was also CEO of Turing Pharmaceuticals, where he raised the price of the cancer treatment Daraprim by more than 5,000%. He currently faces seven counts of securities fraud and conspiracy in connection to previous work at a hedge fund, and he faces up to 20 years in prison if convicted.

“People want yachts,” Butt said. “They want to be rich. The joke is we are all aspiring millionaires. Shkreli actually did it. He’s a hero.”

All aboard the ‘YOLO’ train

Each day, WallStreetBets moderators ask subscribers their planned moves for the session. “All aboard the yolo train,” one recently replied. “Full disclosure I did a bunch of Xanax and drank a bunch of coffee 30 minutes ago.”

Talk of “YOLOing” — going all in on a huge bet — is frequent, if not constant. On March 7, one member announced a move into the penny stock Triangle Petroleum Corp. “Jumped into $TPLM and currently sitting on a mountain of $YOLO waiting for a gap up tomorrow.”

“If you find anything volatile and high risk, that’s where you’ll see people flocking,” Rogozinski said. “Are we encouraging risky behavior? Yes.”

For the past year, the gamble of choice for WallStreetBets followers has been the VelocityShares 3X Long Crude ETN known by ticker as UWTI, which tracks futures contracts on WTI crude oil CLK26, . (ETNs are unsecured debt notes, so investors can lose everything if the underwriter goes bankrupt.)

“UWTI for LIFE baby!!” a subscriber named DrFreshh wrote in December. “History tells you all the patterns. It’s a big time win! Been researching for 20 hours straight (except for the occasional cigarettes). This is it boys and girls! Life savings on the line, we have hit the gold mine. Ask me anything and I can tell you why its bullish like none other, or the yacht is on me.”

When asked how many shares he intended to trade, DrFreshh responded, “100,000. 200,000. that’s pennies. This is an opportunity of a lifetime! I’m gonna invest like its get rich or die tryin.”

Reddit mentions of UWTI, counted by posts with the ticker in the title, went from one in 2013 and 12 in 2014 to 381 in 2015, according to a MarketWatch analysis. In just the first two months of 2016, 124 post included “UWTI” in the title. Most were on WallStreetBets.

UWTI ranked fifth in TD Ameritrade’s top 10 list of shares most traded by millennials in 2015; it wasn’t among the top 10 most traded by older investors. That’s no coincidence, according to Rogozinski.

UWTI is “the 3x leveraged high-risk abstract synthetic derivative of the month for beginners right now,” Rogozinski said. (He has not traded it himself: “I’ve made it past this stage,” he said. “That’s not to say I didn’t trade something similar when I went through my crash course for Wall Street.”)

Most traders don’t hold UWTI for more than a few days; in some cases, they are in and out in minutes. On Jan. 25, it lost more than 22%. On Sept. 1, it sank 21%. Over the past 12 months alone, it’s dropped double-digit percentages on 27 different days, according to FactSet data. Volume, meanwhile, has skyrocketed in 2016.

There were plenty of days with upside, too. UWTI rose more than 13% one day in March. Still, UWTI is down more than 90% in the past 12 months and is now just above $21 per share. In May 2015, when oil was trading above $60 a barrel, UWTI had reached $428.

Even high schooler Rozanski lost on UWTI. He put $500 on it after reading about it on WallStreetBets, losing 20% before selling. But he then booked his big win, riding option bets against the S&P 500 SPX, -1.11% to earn his notorious $900-to-$55,000 profit. (He posted a screenshot to WallStreetBets as proof.)

WallStreetBets has become a “platform for millennials like us to learn about UWTI and lose money,” Rozanski said.

‘No Pity Parties’

The promise of quick money has long been a draw for investors with big ambitions and high tolerances for risk.

“It’s the gambler’s dilemma,” said Jeff Fischer, a longtime adviser for the Motley Fool, who calls the action in WallStreetBet reminiscent of the late 1990s, when traders flocked to the Raging Bull and Silicon Investor sites to tout positions. “As long as you’re making money, you want to keep playing. Almost everyone only stops after they’ve lost.”

F.S. Comeau, a Montreal-area 30-something, recently hung up his WallStreetBets mouse after a stretch that landed him in the doctor’s office. “I lost well over $150,000 on oil from 2014 to 2015,” said Comeau, in an email.

Trade-related stress was making Comeau, who said he made most of that money back trading options on Apple AAPL, -3.17% , miserable — and sick. “I was down by so much I didn’t see my portfolio recovering within years, if ever. I hadn’t slept in 2½ days and I was barely hanging on due to caffeine.”

Reddit might look lawless to an outsider, but each board enforces its own “Reddiquette,” homegrown rules that are near-inviolate on some subreddits. On WallStreetBets, there are two rules: “No Pity Parties” and “Do be responsible giving and taking advice.”

And so while the forum’s tone is gung-ho, many members express concern for their fellow investors, offering protective, if blunt, sentiments. Rogozinski, for his part, said he worries that a huge early win can give new traders a false sense of confidence. “The faster you go up at the beginning, the harder you fall,” he said.

And when one post earlier this year labeled “New to investing” asked about the potential for UWTI to rise to $300 in two years, many responses instead explained that leveraged ETNs decay over time, as well as why UWTI isn't meant to be a long-term holding.

“No offense, but the question posed proves you aren’t ready to make that trade because you clearly haven’t researched what the hell you’d even be buying into,” one commenter responded.

Comeau trades less frequently now, though he doesn’t rule out an eventual return to WallStreetBets. “I’ve spent enough sleepless nights, and I’ve laid long enough in bed with my heart pumping,” he said. “Unless you’ve personally experienced it, you have no idea how hard it is and the toll it can take on your body.”

Young investors are generally encouraged to take on more risk, since time is on their side. But big, all-or-nothing bets on UWTI are particularly dangerous. “Believe me,” said Comeau, “Most of them, if not all of them, will be losing money trading it.”

Teen trader Rozanski, meanwhile, admitted that his big win was “pretty much dumb luck.” He thought about buying a Ford Mustang with his haul, he said, but decided to keep the money to fund future investments, celebrating modestly: His mom took him out to see “The Big Short,” and he bought a new computer with two monitors.

“So I can trade better,” he explained.

Katie Marriner contributed to this story.

This story was first published on March 30, 2016.