This index signaled the 2000 and 2007 crashes—and it's falling again

Stocks with big buyback programs are struggling this year, and according to one technician, a similar lag has previously preceded two market crashes.

Out of the nine S&P 500 companies with the biggest buyback programs, four are down in stock price over the last year. Exxon Mobil,IBM, 21st Century Fox and Merck are all negative for the year, andOracle and Intel are fighting to hold onto incremental gains.  Read more