an investor who bought all of the stocks included in the Dow Jones on Jan. 2, 2001, and sold them on the record-high closing date of 2006 (Dec. 27), gained $3,377.34 — or $2,870.74 after taxes. If, however, the same investor simply converted the money to Canadian dollars on Jan. 2, 2001, and changed them back for U.S. dollars on Dec. 27, 2006, his or her post-tax gain would have been substantially greater ($3,074.64) than it would have been from participating in a “record-breaking” stock market.