NEW YORK (CNN/Money) - Rates for long- and short-term mortgages rose this week as investors pulled some money out of Treasurys, pushing bond yields up, economists said Thursday.

Freddie Mac reported that the 30-year mortgage averaged 6.43 percent in the week ending Aug. 2, with an average of 0.6 of a point payable up front to the lender. The rate rose from an average 6.34 percent last week and remained lower than its average 7 percent a year ago.

The 15-year fixed-rate mortgage averaged 5.84 percent, up from 5.76 percent last week and down from 6.54 percent a year ago. The 15-year averaged 0.6 of a point payable up front.

One-year adjustable-rate mortgages indexed to the Treasury averaged 4.45 percent, with an average 0.6 of a point due up front, up from 4.31 percent last week and down from an average of 5.77 percent a year ago.

"As the stock market rallied this week, investors pulled some money out of Treasurys, pushing bond yields up," Freddie Mac Chief Economist Frank Nothaft said. "This resulted in slightly higher interest rates. But as an offset, gross domestic product for the second quarter came out this week showing weaker-than-expected growth in the economy. Other recently released indicators also suggest slowing growth in July. All of this reduces the risk of inflation and should lessen the upward pressure on interest rates." (Read more about increasing the resale value of a home.)

Freddie Mac (FRE: down $0.47 to $61.48, Research, Estimates), or Federal Home Loan Mortgage Corp., is a publicly traded company the government established in 1970 to provide a flow of funds to mortgage lenders. It buys mortgages from banks, bundles them and then resells them as mortgage-backed securities.

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Its products, and the products of other similar entities, have become increasingly popular as an alternative to government-backed bonds, particularly with international investors.