For several years leading up to his retirement as CEO, the Oracle of Omaha, Warren Buffett, was a net seller of equities. During the June-ended quarter, $23.47 billion in equity securities were purchased, and just $3.69 billion were sold, working out to $19.78 billion in net buying. Even after nearly $19.8 billion in net-purchasing activity in the second quarter, Warren Buffett's and Greg Abel's $366 billion warning to Wall Street echoes louder than ever. This $366 billion warning speaks to the historical priciness of equities and the unwavering value-focused approach of Buffett and Abel. In a rare interview with Fortune magazine in 2001, Warren Buffett referred to the market-cap-to-GDP ratio as "probably the best single measure of where valuations stand at any given moment."