Warren Buffett even makes money while he sleeps. In less than a 24-hour span, Buffett has become $693 million richer.

Yesterday afternoon Buffett purchased $5 billion of Goldman Sachs preferred stock for $115 per share. Goldman’s stock closed yesterday at $125.05. Even before the market opened today, as of 9:20 a.m. ET, Goldman shares trading for $127, 1.35% higher then their close yesterday. That’s a $693 million paper profit for the legendary investor.

To think about this in investment terms, Buffett purchased Goldman stock at a price-to-earnings ratio of about 6.6 yesterday. Today, Goldman’s PE is 7.51, according to Yahoo Finance. Historically, even a 7.51 PE for Goldman is low. Buffett stands to make a lot more than $693 million.

I received a book some weeks back entitled, “Warren Buffett and the Interpretation of Financial Statements.” Perhaps it deserves a closer read?