Here are some quotes from the speech (emphasis mine):
At some point, both lenders and borrowers became convinced that house prices would only go up. Borrowers chose, and were extended, mortgages that they could not be expected to service in the longer term. They were provided these loans on the expectation that accumulating home equity would soon allow refinancing into more sustainable mortgages. For a time, rising house prices became a self-fulfilling prophecy, but ultimately, further appreciation could not be sustained and house prices collapsed. This description suggests that regulatory and supervisory policies, rather than monetary policies, would have been more effective means of addressing the run-up in house prices.
...monetary policy differences explain only about 5 percent of the variability in house price appreciation across countries.
What does explain the variability in house price appreciation across countries? In previous remarks I have pointed out that capital inflows from emerging markets to industrial countries can help to explain asset price appreciation and low long-term real interest rates in the countries receiving the funds--the so-called global savings glut hypothesis...
....the best response to the housing bubble would have been regulatory, not monetary. Stronger regulation and supervision aimed at problems with underwriting practices and lenders' risk management would have been a more effective and surgical approach to constraining the housing bubble than a general increase in interest rates. Moreover, regulators, supervisors, and the private sector could have more effectively addressed building risk concentrations and inadequate risk-management practices without necessarily having had to make a judgment about the sustainability of house price increases.
The lesson I take from this experience is not that financial regulation and supervision are ineffective for controlling emerging risks, but that their execution must be better and smarter. The Federal Reserve is working not only to improve our ability to identify and correct problems in financial institutions, but also to move from an institution-by-institution supervisory approach to one that is attentive to the stability of the financial system as a whole. Toward that end, we are supplementing reviews of individual firms with comparative evaluations across firms and with analyses of the interactions among firms and markets. We have further strengthened our commitment to consumer protection. And we have strongly advocated financial regulatory reforms, such as the creation of a systemic risk council, that will reorient the country's overall regulatory structure toward a more systemic approach. The crisis has shown us that indicators such as leverage and liquidity must be evaluated from a systemwide perspective as well as at the level of individual firms.
Although the house price bubble appears obvious in retrospect--all bubbles appear obvious in retrospect--in its earlier stages, economists differed considerably about whether the increase in house prices was sustainable; or, if it was a bubble, whether the bubble was national or confined to a few local markets.
...having experienced the damage that asset price bubbles can cause, we must be especially vigilant in ensuring that the recent experiences are not repeated. All efforts should be made to strengthen our regulatory system to prevent a recurrence of the crisis, and to cushion the effects if another crisis occurs.
The full speech is available here.