Do not accept principal risk while investing short-term cash: the greedy effort to earn a few extra basis points of yield inevitably leads to the incurrence of greater risk, which increases the likelihood of losses and severe illiquidity at precisely the moment when cash is needed to cover expenses, to meet commitments, or to make compelling long-term investments.

Beware leverage in all its forms. Borrowers - individual, corporate, or government - should always match fund their liabilities against the duration of their assets. Borrowers must always remember that capital markets can be extremely fickle, and that it is never safe to assume a maturing loan can be rolled over. Even if you are unleveraged, the leverage employed by others can drive dramatic price and valuation swings; sudden unavailability of leverage in the economy may trigger an economic downturn.

Below, we itemize some of the quite different lessons investors seem to have learned as of late 2009 - false lessons, we believe. To not only learn but also effectively implement investment lessons requires a disciplined, often contrary, and long-term-oriented investment approach. It requires a resolute focus on risk aversion rather than maximizing immediate returns, as well as an understanding of history, a sense of financial market cycles, and, at times, extraordinary patience.

Avoid organizing investment team into silos.

To achieve long-term success over many financial market and economic cycles, observing a few rules is not enough. Too many things change too quickly in the investment world for that approach to succeed. It is necessary instead to understand the rationale behind the rules in order to appreciate why they work when they do and don't when they don't.

Financial innovation can be highly dangerous, though almost no one will tell you this. New financial products are typically created for sunny days and are almost never stress-tested for stormy weather. Securitization is an area that almost perfectly fits this description; markets for securitized assets such as subprime mortgages completely collapsed in 2008 and have not fully recovered. Ironically, the government is eager to restore the securitization markets back to their pre-collapse stature.

Value investors will not invest in businesses that they cannot readily understand or ones they find excessively risky. Hence few value investors will own the shares of technology companies. Many also shun commercial banks, which they consider to have unanalyzable assets, as well as property and casualty insurance companies, which have both unanalyzable assets and liabilities.