Valuations for U.S. equities have been stuck below the five-decade average for the longest period since Richard Nixon’s presidency, a sign that investors don’t trust earnings even after a three-year bull market, Bloomberg reported.

Analysts estimate profits in the Standard & Poor’s 500 index will reach a record $104.78 per share this year after increasing 125 percent since the end of 2009, the fastest expansion in a quarter-century, according to data compiled by Bloomberg.

American companies are boosting income so much that even after stocks doubled, the S&P 500 hasn’t traded above its 16.4 mean price-earnings ratio for 446 days, the longest stretch since the 13 years beginning in 1973.

Investors are staying away from stocks, even after record profits, 10 quarters of U.S. economic growth and promises by the Federal Reserve to keep interest rates near zero through 2014.

An average of 6.69 billion shares traded on U.S. exchanges in the 50 days ended Jan. 18, the fewest since at least 2008, according to data compiled by Bloomber