Costco trades by members of Congress

When several House members traded Costco

Months when 2 or more House members became net buyers, or 3 or more net sellers, of Costco in reports dated in the 91 days before the month end, and how the stock did against the S&P 500 from that month end. Only House members' electronic trade reports are included; Senate reports and reports filed on paper are not. After the 17 buying crowds with six months of prices, it averaged +2.1% against the index. After 6 selling crowds, +5.4%. One company's history is too short to judge by; the test across every company is the better guide.

Colours show whether the crowd was right: green when buyers were followed by a rise above the index, or sellers by a fall below it. Latest 12 of 23. Total returns from the month end; past patterns are not a forecast.