BALTIMORE ( Stockpickr) --Today's the first trading day of October. That means we're starting both a new trading month and quarter today -- an opportunity for investors to reset their mental clocks as they gauge short-term performance. From a psychological standpoint, that reset could have an important bearing on investors' risk appetite.The start of the fourth quarter is important for another reason too. Historically, the fourth quarter is one of the best-performing periods for stocks, accounting for nearly half of the market's average annual gains. Obviously, that seasonality is far from guaranteed any year - especially when black clouds are looming overhead. Even so, it's a statistic worth considering as we enter the fourth quarter of 2011. >>5 Big Stocks to Trade for Gains Of course, if you're looking for performance, Rocket Stocks have historically been a good choice as well. In the last 123 weeks, our weekly list of five names has outperformed the S&P 500 by 85.1%. This week, we'll aim to continue beating the market with another set of stocks. For the uninitiated, Rocket Stocks are our list of companies with short-term gain catalysts and longer-term growth potential. To find them, I run a weekly quantitative screen that seeks out stocks with a combination of analyst upgrades and positive earnings surprises to identify rising analyst expectations, a bullish signal for stocks in any market. After all, where analysts' expectations are increasing, institutional cash often follows. With that, here's a look at this week's Rocket Stocks.