Global risk rally has a powerful ally: the weaker dollar

Investors are betting a weaker U.S. dollar will further boost a rally that has seen stocks, emerging market currencies and other risky assets soar in recent weeks.The dollar is down 6.6% against a basket of currencies from a more than three-year high in late March, the sharpest 21-day drop in about 2 years.Several factors are driving the dollar lower.