Here is the info on money manager sentiment via the Barron's article "Dow 16,000" (April 22, 2013):
"The stock market isn't the only thing that has set records this spring. Barron's semiannual Big Money poll of professional investors also is setting a record -- for bullishness, that is. In our latest survey, 74% of money managers identify themselves as bullish or very bullish about the prospects for U.S. stocks -- an all-time high for Big Money, going back more than 20 years. What's more, about a third of managers expect the Dow Jones industrials to scale the 16,000 level by the middle of next year, notwithstanding a dismal week of selling that left the blue-chip index at 14,547.51 on Friday."
Here are charts and tables of NYSE Margin Debt (in millions) versus the S&P 500 going back to 1959.
Look how the market immediately crashed 20% when margin debt went vertical in 1987. The S&P actually peaked one month before margin debt did in 1987. As you can see in the chart above, leverage never really recovered from the crash until the early 90s, but the S&P recovered immediately. The Federal Reserve lowered the federal funds rate by 1/2-3/8 after the crash, so that probably helped juice stocks. Plus the secular bull market was alive and well at that time.
The market corrected 17% when margin debt went vertical in 2011.
After margin debt peaked in 3/2000, the bull market eventually peaked in 8/2000. So there was a 5 month lag.
Lastly, after margin debt peaked in 7/2007, the S&P peaked in 10/2007 (3 month lag).