Down More Than the S&P 500 and Nasdaq, Is Warren Buffett-Led Berkshire Hathaway's Second Largest Holding a Buy Now?

Berkshire Hathaway's (BRK.A 0.17%) (BRK.B -0.12%) assets have changed considerably in recent years. Today, the value of Berkshire's controlled companies exceeds its public equity portfolio. Even Berkshire's cash, cash equivalents, and marketable securities are worth more than its stock holdings.Berkshire has reduced its stake in top holdings such as Apple and Bank of America. But one position that has stayed the same for decades is American Express (AXP 0.97%) -- which now makes up 14.5% of the equity portf ...