By Tess Stynes 
 

Average fixed mortgage rates in the U.S. rose in the latest week, marking the largest one-week increase this year, according to Freddie Mac (FMCC).

Fixed mortgage rates also reached the highest level since the week ended May 1, the mortgage-finance company said.

Freddie Mac Chief Economist Frank Nothaft noted in a statement Thursday that the jump in fixed mortgage rates followed an increase in 10-year Treasury yields that was partly fueled by market speculation that the Federal Reserve might change its guidance on when it will raise interest rates.

For the week ended Thursday, the 30-year fixed-rate mortgage averaged 4.23%, compared with 4.12% a week earlier and 4.5% a year earlier. Rates on 15-year fixed-rate mortgages averaged 3.37%, compared with 3.26% the previous week and 3.54% a year earlier.

Five-year Treasury-indexed hybrid adjustable-rate mortgages, or ARMs, on average, were at 3.06%, compared with 2.99% the previous week and 3.11% a year earlier. One-year Treasury-indexed ARM rates on average were 2.43%, compared with 2.45% the previous week and 2.65% a year earlier.

Write to Tess Stynes at tess.stynes@wsj.com