I use William O'Neill's method (although he may have updated it in recent years) for tracking distribution on the NASDAQ, S&P500, and DJIA. Rising volume when an index either declines or gives back almost all of an intraday advance indicates distribution. A decline of 1% or more with rising volume is major distribution.
I track distribution days in three week window. Four days of distribution followed by a fifth day of major distribution signals a breakdown and is usually followed by a 15-20% decline.