U.S. stock market investors hammered share prices of many companies last month. But one company with Hawaii ties has been beaten down particularly hard.

Shares of Pacific Office Properties Trust, which owns a collection of office buildings largely concentrated in Honolulu, ended last week at 61 cents.

The stock is now worth about one-tenth what it was when local real estate investor Jay Shidler took Pacific Office public three years ago, and has fallen 70 percent in the past month from what had been a fairly stable level for most of this year around $2.

Pacific Office’s recent stock slide, which began July 22, doesn’t appear to be a casualty of general stock volatility or reaction to public announcements by the company.

Mike Hamasu, research analyst with local commercial real estate firm Colliers Monroe Friedlander, said the trouncing of Pacific Office stock is surprising given that Honolulu’s office market is relatively healthy compared with most mainland cities and because real estate investment trusts, or REITS, have generally outperformed the broad stock market.

Several other large U.S. office REITS saw their stocks punished severely early last month only to regain much of the loss. There has been no such rebound for Pacific Office.

The NYSE Amex stock exchange, on which Pacific Office stock is traded, notified the company about the unusual activity, and the company said last week that its policy is not to comment on such activity.

Roughly 1,100 public shareholders own stock in Pacific Office, though they own relatively minor stakes in the company.

The bigger impact, at least on paper, is on Shidler and his partners who formed Pacific Office and still retain roughly 80 percent of the total equity in the firm, including about 51 percent of publicly traded stock, public filings show. Company co-founder James Reynolds Jr. is the second-largest shareholder.

Pacific Office differs from typical public companies because of how it was formed. Shidler owned several buildings with partners in privately held local firm The Shidler Group, which contributed several buildings to an operating partnership. An unrelated company with public stock shares that was liquidating assets contributed cash to the entity known as an umbrella partnership REIT.

Because the value of the buildings far outweighed the cash contribution, Shidler’s group retained overwhelming ownership in Pacific Office through shares of stock as well as senior common stock and operating partnership units that aren’t traded like regular shares.

Combined equity stakes gave Pacific Office a market value last week of about $12.5 million, of which Shidler’s group owns about $9.7 million. That compares with a total market value of about $750 million when the company went public in March 2008.

Shidler initially contributed eight buildings to the company, including six in Honolulu — Waterfront Plaza, Davies Pacific Center, the Pan Am Building, First Insurance Center, the Pacific Business News Building and Clifford Center. One building in San Diego and one in Phoenix also were contributed, as was a 7.5 percent interest in a ninth building in San Diego.

Shidler said at the time he intended to acquire more buildings with co-investors while counting on Honolulu as the investment core to become a hot market with tight vacancies and rising rents.

Pacific Office did expand its portfolio primarily by acquiring minority ownership — between 5 percent and 32 percent — in 16 office properties, including one in Honolulu, Bank of Hawaii Waikiki Center.

But financial and real estate markets took a tumble with the recession, and Pacific Office encountered trouble raising capital and paying some building mortgages.

The company tried twice to sell additional stock to generate cash to reduce debt and expand holdings, but the attempts fizzled. The most recent try in January contemplated selling shares for between $7.50 and $8.50.

The aborted stock sales added expenses to company operations and contributed to financial losses. Net losses — $78 million last year and $23 million the year before — were among factors that prompted NYSE Amex to warn Pacific Office in April that it was in danger of being delisted. For the first six months of this year, the company posted a $17 million net loss.

Pacific Office has submitted an acceptable plan to NYSE Amex that will allow its stock to continue to trade as long as Pacific Office reconforms to listing standards by Oct. 19, 2012.

The company also embarked on a plan to sell partial or whole interests in some of its Honolulu buildings as a way to recapitalize.

In May, Pacific Office announced a deal to sell partial ownership in the Pacific Business News Building in Waikiki and a three-tower office complex in Phoenix called City Square to New York investment firm Angelo, Gordon & Co.

The two properties were tied to $64 million in overdue mortgage debt, which got paid off with the sale.

On Aug. 15, Pacific Office issued a detailed financial report that reaffirmed its strategy to sustain operations using about $5 million in existing cash, any positive cash flow and sales of partial or whole interests in buildings.

The report also disclosed that Pacific Office had stopped making debt service payments on a loan secured by a building in San Diego called Sorrento Technology Center, which it wholly owns. Pacific Office said it is negotiating to modify the delinquent loan.

"Our business is capital intensive and our ability to maintain our operations depends on our cash flow from operations and our ability to raise additional capital on acceptable terms," the company said in the report. "We are currently focused on preserving cash and intend to limit the amount of discretionary funds allocated to capital expenditures and leasing costs in the near term."

Pacific Office also warned that the conservation effort could hinder the number of new tenant leases and rental rates.

But Larry Taff, Pacific Office executive vice president, said the company will keep pushing ahead with its expansion and debt-reduction strategy while maintaining existing properties.

"The portfolio has got a lot of really quality assets in good markets," he said. "I think we’re well positioned to take advantage of market recovery."

On Wednesday, Pacific Office announced that it bought an office building in Santa Clarita Valley, Calif., with Angelo Gordon for $31 million. Pacific Office didn’t disclose its stake, but it is less than 32 percent.

Shares of Pacific Office stock rose one cent on Thursday to 64 cents after news of the purchase was released.