There seems to be no end to the number of real estate investment trusts (REITs) making secondary stock offerings these days. Why? Because apparently investors can't get enough of a good thing.

Total returns from REIT stocks have been on the up and up in 2010, mostly. While the FTSE NAREIT U.S. real estate return index fell 4.68% in January, it rose 5.06% in February, 9.42% in March and 6.58% in April, before falling again, by 5.32%, in May.

Those performance metrics were enough to spur a series of secondary offerings as REITs tap investors for more capital. On Friday, HCP Inc. (NYSE: HCP) priced a public offering of 13.5 million shares at $33 per share, which the REIT expects will raise more than $445 million. The company increased the offering from 12 million shares due to investor demand.

Long Beach, Calif.-based HCP specializes in senior housing, medical office buildings, hospitals and other healthcare facilities. It owns or has interests in 677 properties, and said proceeds would repay borrowings under its revolving credit facility, part of which had been used to acquire four senior housing facilities.

The underwriters – BofA Merrill Lynch, UBS Investment Bank and Wells Fargo Securities – also have an option to purchase up to 2.025 million shares of common stock exercisable within 30 days. HCP’s shares closed down $1.63, or 4.75%, to $32.72 on Friday June 18.

Also last week, Indianapolis-based Duke Realty Corp. (NYSE: DRE) priced a public offering of 23 million shares of its common stock at $11.75 per share. Duke also granted the underwriters a 30-day option to purchase up to 3.45 million additional shares of common stock to cover over allotments, if any.

The REIT owns about 135 million sq. ft. of industrial, office and medical office properties nationwide. It intends to use the net proceeds from the offering to fund the recently announced acquisition by Duke Realty Limited Partnership of its joint venture partner's 50% interest in the Dugan Realty, L.L.C. joint venture, to repay debt and for general corporate purposes.

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