Excellent post from tradinggoddess blog on stocks with 40% moves:

6. Stocks of companies that beat the analysts’ consensus estimate (if there is one) by a wide margin. Such companies report triple digit quarterly EPS growth and significant rise in sales. Boosted guidance for future earnings also help. Market tends to respond enthusiastically to such news, sending the price of a stock in the sky on monstrous volume.

7. Stocks, belonging to currently hot sectors. For example if several coal producers report significant earnings growth on favorable market conditions, it is very likely that Wall Street will bid up stocks of other members of the same sector, even when the fundamentals of those other members are far from impressing. Investors’ expectation for future earnings is a key here.