CHARLESTON, W.Va. -- A Boston-based investment company that was the second-largest investor in Massey Energy recently sold most of its stock in the company.

On March 31, Wellington Management Co. owned nearly 5.8 million shares in the Richmond, Va.-based Massey, according to U.S. Securities and Exchange Commission documents. That was 5.63 percent of Massey's common stock, then worth more $303.1 million.

According to a July 12 statement, Wellington had sold 85 percent of its Massey stock holdings. It now owns 833,155 shares -- less than 1 percent of the company's stock -- according to a Massey filing with the SEC.

A Wellington spokesman declined comment on the stock sale.

Massey stock closed at $54.58 on April 5, the day a mid-afternoon explosion killed 29 miners at the company's Upper Big Branch Mine in Raleigh County.

Massey shares sold on July 12 at $28.28. When the stock markets closed Friday, shares were at $28.15.

The SEC requires all publicly traded companies to reveal the names of all corporate or individual shareholders who own more than 5 percent of their publicly traded stock.

According to the Massey SEC filing on July 12, Wellington owned only 0.86 percent of its stock after the sale.

On March 31, two other investment companies also owned more than 5 percent of Massey stock, according to SEC filings.

FMR LLC, an investment company based in Boston, owned 9.2 percent, while BlackRock Advisors, an investment company in New York City, owned 5.3 percent of Massey's stock. There was no indication that those companies had reduced their stock in Massey.

Wellington Management handles more than $535 billion in investments in stocks and bonds in more than 60 countries, according to its website.

Reach Paul J. Nyden at pjny...@wvgazette.com or 304-348-5164.