Rates of return

Here are annualized rates of return for absolutely clear vs. absolutely cloudy days over the period studied.

New York

All days: 16.0 percent

Clear days: 24.8 percent

Cloudy days: 8.7 percent

Foreign exchanges

(25 markets combined.)

All days: Not available

Clear days: 45 percent

Cloudy days: 16 percent

SOURCE: Charles A. Dice Center for Research in Financial Economics