You can always short the stock, but that is quite risky as your maximum downside is theoretically infinite (the stock can always go up). A bearish options strategy[1] can at least define your risk. Thinkorswim[2] options platform is my favorite, they were acquired by TD Ameritrade a while ago, but the thinkorswim platform is still independent from the larger TD Ameritrade system.

[1] http://en.wikipedia.org/wiki/Options_strategies [2] www.thinkorswim.com