A growing number of traders are betting Snap’s stock price will fall

An example will explain it better though.. Imagine a random trading instrument, any will do. The bid is $100, the ask is $101. Say there are 50 bids showing, and 500 asks. At first glance, this looks like it's prime for selling..enter the coin flip traders. They sell it 5, 10, 20 contracts at a time, all small lots. Magically though the bid sits at 50 no matter what the retail traders throw at it...

That's the coin flip traders at work, selling into what looks like a weak market. I'm the 50 bid at $100(and I'm 400 of the 500 asks at $101, but you don't know that yet), and my order is set to keep stacking up to 1000-2000 bids, all while keeping the shown number under 50(as in, if you sell 5 of them, I'll add 5 more to stack the bid back to 50). Once the coin flip traders get tired of selling, or I get tired of waiting, I'll pull my 400 orders off the ask, so now it shows 100. Then I'll throw 1500-2000 at the ask, and push the price up 4 ticks - right into your average retail coin flipper's stop loss...now those sellers become buyers whether they like it or not, and the market goes in my direction.

Rinse and repeat, rinse and repeat, rinse and repeat... as long as suckers show up to play, pros will be waiting to play them. I'm not one of those pros, I'm just the guy riding along their coat tails. I'm a very small fish, and there are massive sized whales doing the same thing with 500 to 1000 times the leverage I have. They also can afford to play more "tricks" on the coin flip traders. In that example scenario, someone bigger than me will actually drop the market against themselves 2 to 3 more ticks, encouraging suckers to sell into it before yanking the rug out from under you. Only retail coin flip traders fall for this though, the pros and the banks see what is going on, and will join in on the side against the retail lots. The reason they are picking on the retail people is because retail stops are predictable - average guy holding Facebook or Snap or anything else can't afford for the market to move against them much and will place their stops shallow as a result. The pros and banks can take more pain though, so they are harder targets. If it only takes 5mil of leverage to stop out retail, but it takes 50mil of leverage to stop out the pro/bank making the play, which do you think they will pick? The 5mil for the low hanging fruit.

You can sum all this up as... if you aren't trading every day, for <X> years of your market: don't do it. The odds are orders of magnitude worse for amateurs than the loosest casino in Las Vegas. Calling it a coin flip is probably a disservice, because your odds are way less than 50%. You are going to lose, and you are going to lose quickly.