The euro fell to a three-week low against the dollar as traders worry whether enough investors will participate in a Greek bond swap deal happening this week, according to AP. Greece needs to complete the debt restructuring to get its second package of bailout funds and avoid a default. Investors holding Greek debt will have to accept a lower value on their bonds and also lower returns. A dozen big firms said Monday they would participate in the program, but traders are concerned that not enough firms will participate. The deadline to do so is Thursday. The euro fell to $1.3126 in morning trading Tuesday from $1.3224 late Monday. The euro fell as low as $1.311 early Tuesday, its lowest point against the dollar since Feb.16.