Utility stocks were little changed as Treasury yields climbed amid a lack of fresh economic data.

Iberdrola said it reached a deal to buy a majority stake in Finland's main electricity distributor for 2.01 billion euros ($2.29 billion). The acquisition of 80% of the share capital of Caruna Group strengthens the Spanish utility's position in Finland, which it called "a market with high credit quality and a stable and attractive regulatory framework." Caruna Group is currently owned by a Dutch entity controlled by the Ontario Teachers' Pension Plan and funds managed by KKR. The deal gives the distributor an enterprise value of around 5 billion euros, Iberdrola said.

American Electric Power named David Marriott, Chairman of the Board of Marriott International, and Charles Meyers, Executive Chairman and former President and Chief Executive Officer of Equinix, to its board of directors.

U.S. natural gas futures ended a rangebound session near flat as cooling demand in the south and central U.S. is tempered by milder temperatures in the east and prospects that Tropical Storm Bertha could interrupt LNG exports in the Gulf and bring cooling rains to parts of Louisiana and Texas.

Write to Patrick Sullivan at patrick.sullivan@wsj.com