One thing that keeps things in check in the equities market is the fact that there are a lot of strings attached to the market that prevents the market from over reacting to every bit of event. Some of these include the Federal Reserve, interest from powerful folks around the work the wealthy trading volume, the strength off the economy, to name just a few.
For bitcoin to be even remotely as stable as stocks, player in this field need to work more aggressively to get the digital currency attached to a number of heavy strings.