Yahoo, Countrywide Boost Top Line With New Revenue Sources; Firms adjust to changing markets by adding to their existing offerings.(LEADERS & SUCCESS)(MANAGING A SUCCESSFUL COMPANY)

Byline: PAUL KATZEFF

Grow or die. That's the ugly reality that CEO confront every morning.

Boosting profit by cutting costs typically works only temporarily. And you can't always squeeze more revenue out of existing business lines. The best way to grow your bottom line is usually to grow your top line.

Countrywide Financial and Yahoo have grown by diversifying their product and service offerings.

Diversification is defensive. It's moved both Countrywide and Yahoo away from depending on the health of one type of business activity. That's especially reassuring when the economy is wobbly.

Countrywide, a holding company for America's largest independent residential mortgage lender, knows the importance of weaning itself away from heavy reliance on lending. Interest rates can't stay low forever. Rising rates could put a major dent into the …