HCP Inc. shares fell slightly Tuesday morning after the health care real estate investment trust said it would sell 7.8 million shares of its common stock in a public offering.

If the Long Beach REIT shares had sold at Monday’s closing price of $43.62, the offering would have raised about $340 million, but up to $391 million including the underwriter’s overallotment option. HCP now has more than 419 million shares outstanding.

After the markets closed on Monday, HCP said it would use net proceeds from the offering to repay indebtedness, including about $250 million in 6.45-percent senior notes that are due to mature on June 25. Any remaining money will be used for general corporate purposes, including possible acquisitions or investments.

Citigroup is sole underwriter of the offering. It has an option to purchase up to 1.17 million additional shares to handle any overallotments. The offering is expected to close on June 22.

Shares were down $1.11, or 2.5 percent, to $42.51 in midday trading on the New York Stock Exchange.