Public Service Co. of Colorado issued $750 million of first mortgage bonds in two tranches.

The company sold $375 million of 2.70% series 35 first mortgage bonds due 2051 and $375 million of 1.90% series 36 first mortgage bonds due 2031.

The interest is payable semiannually Jan. 15 and July 15, starting Jan. 15, 2021, according to a May 8 prospectus. Both series are expected to be rated A1 by Moody's, A by S&P Global Ratings and A+ by Fitch Ratings.

The 2.70% bonds carry a spread to benchmark Treasury of 140 basis points, and the 1.90% bonds carry a spread of 125 basis points.

The company will use the proceeds from the offering to finance or refinance eligible green projects from January 2019 to December 2020; redeem outstanding long-term debt, including $400 million of the 3.20% series 20 first mortgage bonds due November 2020; and for general corporate purposes. Until the proceeds are used for these purposes, they will be invested temporarily in interest bearing obligations, including investments in the utility money pool.

CIBC World Markets Corp., J.P. Morgan Securities LLC, KeyBanc Capital Markets Inc., TD Securities (USA) LLC, Citigroup Global Markets Inc. and Scotia Capital (USA) Inc. were book managers. BMO Capital Markets Corp., BNY Mellon Capital Markets LLC and Fifth Third Securities Inc. were co-managers.

Public Service Co. of Colorado is a subsidiary of Xcel Energy Inc.