Martin J. Whitman is another well-regarded value investor. His approach is called safe-and-cheap, which was hitherto referred to as financial-integrity approach. Martin Whitman focuses on acquiring common shares of companies with extremely strong financial position at a price reflecting meaningful discount to the estimated NAV of the company concerned. Whitman believes it is ill-advised for investors to pay much attention to the trend of macro-factors (like employment, movement of interest rate, GDP, etc.) because they are not as important and attempts to predict their movement are almost always futile. Whitman's letters to shareholders of his Third Avenue Value Fund (TAVF) are considered valuable resources "for investors to pirate good ideas" by Joel Greenblatt in his book on special-situation investment "You Can Be a Stock Market Genius".