Conclusions (Day Trading) [from the nasaa study]
There was only one successful day trading account in the 17 accounts analyzed.
Fifteen of the 17 accounts analyzed had a significant risk (probability of ruin over 27.6%) of losing all funds. Eleven of these 17 accounts had a 100% chance of ruin.
That is, 65% of these accounts would almost certainly lose any and all funds put at risk in them.
Five of the six accounts, which realized net profits, were no more than marginally profitable and realized a large percentage of their profits from a single trade.
Speculative trading is volatile. Clearly, if a trader can make most of his or her profit on a single trade, he or she can lose it on one or two trades. Moreover, it should also be noted that any profitability evaluation must be conducted on a risk/reward basis. If you have 5 times the risk, you should require at least 5 times the reward.
The Sharpe Ratio compares the return from an investment with the risk incurred to earn the return. A risk/return analysis was conducted for account A30, the only account considered successful in both day and short-term trading. The Sharpe Ratio analysis (Exhibit I) clearly shows that although Account A30 was profitable, it did not produce a return commensurate with the risk to which it was exposed.
The Bottom Line
If this analysis is representative of public trading, it is abundantly clear that the average public investor should refrain from short-term trading. Only three (3) of twenty-six (26) accounts (11.5% of the sample) evidenced the ability to conduct profitable short-term trading. This study shows that 70% of the public traders will not only lose, but will almost certainly lose everything they invest.
Day trading is particularly risky. While the study found that three (3) accounts in twenty-six (26) could successfully conduct short-term trading, there was only one successful day trading account.
A Sharpe Ratio analysis of the only account considered successful in both short-term and day trading showed the trading returns were not commensurate with the risks to which the account was exposed.
The most successful account in the study, A8, had limited short-term trades and no day trading.
http://www.nasaa.org/content/Files/Day_Trading_Analysis.pdf