Market-wide insider sentiment: how many companies have insiders buying their own stock vs how many have them selling, compared with the same time in past years.
Everything comes from the filings officers and directors make with the SEC when they buy or sell their company's stock on the open market.
Left out: sales under pre-arranged 10b5-1 trading plans (they are scheduled months ahead, so they say little about today), 10% owners, funds that sit on company boards,
and trades reported more than four weeks late. Awards, option exercises and gifts aren't open-market trades and aren't counted either.
Why compare with the same time in past years
Insiders can usually only trade in the weeks after their company reports earnings, so insider buying and selling both rise and fall with earnings season.
That is why the latest 30 and 90 days are compared with the same 30 and 90 days in previous five years, and each month in the chart with the same month
in earlier years, rather than with an average month.