Not surprisingly, we try to identify unusual patterns in valuations, such as historically high or low ratios of prices to earnings in equity markets. We use a variety of models and methods; for example, we use empirical models of default risk and risk premiums to analyze credit spreads in corporate bond markets. These assessments are complemented by other information, including measures of volumes, liquidity, and market functioning, as well as intelligence gleaned from market participants and outside analysts. In light of the current low interest rate environment, we are watching particularly closely for instances of "reaching for yield" and other forms of excessive risk-taking, which may affect asset prices and their relationships with fundamentals. It is worth emphasizing that looking for historically unusual patterns or relationships in asset prices can be useful even if you believe that asset markets are generally efficient in setting prices. For the purpose of safeguarding financial stability, we are less concerned about whether a given asset price is justified in some average sense than in the possibility of a sharp move. Asset prices that are far from historically normal levels would seem to be more susceptible to such destabilizing moves.

David Fuller's view I do not know if Mr Bernanke is trying to reassure us or warn us but this sentence near the middle of the paragraph has raised a few eyebrows:

In light of the current low interest rate environment, we are watching particularly closely for instances of "reaching for yield" and other forms of excessive risk-taking, which may affect asset prices and their relationships with fundamentals.

You may also wish to read the rest of the paragraph. I assume that he is mainly talking about so-called junk bonds but it could be more of a general comment following the very strong stock market advance since mid-November 2012. Inevitably, Mr Bernanke must be thinking about an end to QE, even if he is no longer Chairman of the Fed when it occurs.