NEW YORK (MarketWatch) -- Treasury prices extended gains slightly and the dollar fell more against the Japanese yen and Swiss franc on Monday after the Institute for Supply Management's index on U.S. manufacturing fell much more than expected in July. The dollar lost 0.9% against the Japanese yen and almsot 2% versus the Swiss franc USDCHF -2.08% after the data. The dollar index DXY +0.32% , which tracks the U.S. unit against a basket of six major currencies, traded at 74.171, compared to 73.961 before the report and up from 73.846 late Friday, supported by losses in the euro just before the data. Yields on 10-year notes 10_YEAR -1.54% , which move inversely to prices, fell 5 basis points to 2.76%, from 2.79% before the data.