I lost about $3,000 in a legal stock market scheme I fell for. It was an indexed "fund" called UWTI, which paid 3x the change in the price of crude oil. I bought when oil had dropped to around $50/barrel (I think), with the knowledge that it would eventually go up. What I didn't realize is the simple mathematical fact, that if you take any number, increase it by a certain percent, and then decrease it by the same percent, the net result is a decrease. (start with 100, go up 10%, it's 110, now go down 10%, it's 99. Those fluctuations up and down eventually turn that 100 to zero!). I didn't realize this, and left my money in that "fund", and didn't check it for a few months, and it was whittled down to almost nothing. A friend of mine at work was big into stock trading, and I listened to him talk this thing up, and when you looked at their chart (obviously rigged), it made it seem that if oil got back up above $100/barrel, the value of the fund would be through the roof. What I didn't recognize is that they must have had a few people in on the scheme early on, so that it made it look like people actually paid (maybe they did, but it was part of the scheme) thousands of dollars per "share" when oil WAS over $100/barrel, so a casual view of that trend would leave stupid people, like me :) , to believe you could also see a rise. But, I didn't count on those daily, even hourly, or even at the minute level, fluctuations that ate the value away. After I got what I could back, I continued to watch the fund, and it eventually got to such a low value it was shut down. The original people involved must have made 10s of millions from it. I tried to get SEC to investigate. I provided them with a summary of the scheme, but they never got back to me. What is funny, is this "fund" had a 90-page "prospectus". I didn't read through it all, but perhaps somewhere around page 88 it described how the fund was worthless and anyone who left their money in it for more than a day was an idiot :)