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The magnitude of the decline of the 12-month, as-reported S&P 500 earnings is unprecedented (the data goes back to 1936) with 90% over the past 20 months (with over 90% of S&P 500 companies having reported for Q1 2009).
Real earnings have dropped to a record low and if current estimates hold, Q3 2009 will see the first 12-month period during which S&P 500 earnings are negative.