Mortgage rate dropped slightly last week, as homebuyers may have an opportunity window to buy in the U.S. housing market, the U.S. Federal Home Loan Mortgage Corporation, commonly known as Freddie Mac, said on Thursday.

For the week ending Jan. 3, 30-year fixed-rate mortgage (FRM) in the United States dropped to 4.51 percent from previous week's 4.55 percent, according to Freddie Mac.

For the same period a year ago, the 30-year FRM averaged 3.95 percent, according to Freddie Mac.

"Mortgage rates declined to start the new year with the 30-year fixed-rate mortgage dipping to 4.51 percent. Low mortgage rates combined with decelerating home price growth should get prospective homebuyers excited to buy," said Sam Khater, chief economist of Freddie Mac.

"However, it will be interesting to see how the recent turmoil in the stock market will affect homebuying activity in the coming months," Khater added.

Freddie Mac also said that 15-year FRM this week dropped to 3.99 percent, which was lower than previous week's reading of 4.01 percent. For the same period a year ago, the figure was 3.38 percent.

Freddie Mac is a corporation founded by U.S. Congress, aiming at promoting the stability and affordability in the U.S. housing market by purchasing mortgages from banks and other loan makers. The corporation has been conducting weekly surveys on U.S. mortgage rate since April 1971.