I would guess that if this is really a world cup effect, then the loss would be in the price at the open. Since most of these games take place in the evening, in order to make the -0.49% return, you would have to successfully forecast the result of the game, in which case you could probably do better by betting. I suppose that there might have been a trade here during the Japan/Korea world cup games, but since the cup is being held in the same time zone as most of the football-playing countries with liquid stock markets, I wouldn't get hopes up on this one.