Four funds that profit when prices fall. By Elizabeth Leary, Contributing Editor July 3, 2008 Despite the recent run-up in bond yields, current returns from Treasuries remain paltry. If you think yields will continue to climb -- a reasonable assumption given the growing concern about inflation -- there are easy ways to make money. ProFunds offers two mutual funds and two exchange-traded funds that gain along with falling Treasury prices (which move inversely with yields). The regular funds are ProFunds Rising Rates Opportunity 10 (symbol RTPIX) and ProFunds Rising Rates Opportunity (RRPIX). The ETFs are ProShares UltraShort Lehman 7-10 Year Treasury (PST) and ProShares UltraShort Lehman 20+ Year Treasury (TBT). If, say, the price of the ten-year Treasury note drops 1% in a day, Rising Rates Opportunity 10 should gain 1% that day. The other three funds use leverage to magnify returns. For example, both ETFs seek to double the inverse of the daily price return of their respective indexes. Each fund made money this spring as yields rose. For example, from the ten-year Treasury's low yield on March 17 to June 9, Rising Rates Opportunity gained 4.5% and Opportunity 10 returned 3.3%. But, by definition, these funds will suffer when rates fall. Exercise vigilance.