Shares of Pacific Office Properties Trust Inc., a struggling real estate investment trust focused on commercial offices, plummeted last week leading up to an expected public offering.

The REIT, with dual offices in Santa Monica and San Diego, trades on NYSE Alternet but plans to move to the Big Board with an offering of 44 million shares, likely this week.

The shares are expected to be priced about $8 to raise $325 million in net proceeds, most of which would go toward acquiring a $306 million portfolio and paying down debts.

But the share price slid 39 percent last week on high-volume trading. The company was the top loser by percentage in the LABJ Stock Index last week, closing at $2.59 on Jan. 5. (See page 24)

Lloyd Greif, president of downtown L.A. investment banking firm Greif & Co., said that investors were likely scared off by the offering’s price tag, which is much higher in proportion to its financial footing than with other REIT stock offerings.

The company reported revenue of $72.6 million in 2009, according to a Securities and Exchange Commission filing.

“The issue here is that the valuation is optimistic,” he said. “It’s a gamble that the company is taking and some of the shareholders seem like they don’t want to be a part of that gamble.”

Pacific Office Properties and Wells Fargo Securities, one of the lead underwriters, declined to comment.

Comments left by shareholders on an online message board also expressed concern about the value of their shares after the offering. The company’s market cap as of Jan. 5 was $50.1 million.

“Usually when an offering does file, it dilutes the ownership percentage and it’s not unusual for a stock to trade down, but this kind of movement is pretty dramatic,” Greif said.

The proceeds would go toward acquiring 12 office properties in San Diego, Orange County, Los Angeles and the Bay Area from Boston-based Guggenheim Real Estate.

The REIT owns eight office properties and an interest in 16 joint-venture properties, with much of its holdings in Honolulu. It has been losing money for several years and reported a $1.8 million loss in the third quarter.

Pacific Office Properties is managed by real estate investment organization the Shidler Group. It was formed in 2008 when two of the Shidler Group’s private entities conducted a reverse merger with an existing REIT. Shidler founder Jay Shidler is chairman of Pacific Office Properties.