TAMPA — Walter Investment Management Corp., a long-troubled subprime mortgage company based in Tampa, filed for bankruptcy reorganization Thursday. The prepackaged bankruptcy filing follows an October announcement that the firm was being restructured to reduce its significant debt."The actions taken today are intended to reduce the company’s debt, strengthen its balance sheet and better enable Walter to focus on its business," the company said in a statement.The restructuring, which will finish in the first quarter of 2018, will cut down the company’s debt by $800 million, Walter Investment said. Two of Walter’s subsidiaries, Ditech Financial and Reverse Mortgage Solutions, are not expected to file bankruptcy.Walter intends to continue operations through the restructuring and filed for permission to do so."We are making significant progress transforming our business, and the financial restructuring contemplated by the agreements we have reached with our lenders and note holders are a key part of our plans," Walter CEO Anthony Renzi said in October.Renzi took over as CEO about a year ago as the firm’s 2016 revenue had sunk to $995 million from about $1.3 billion in 2015.Once a high-performing bay area public company, Walter’s stock has been trading under a dollar. Shares closed Friday up 36 percent at 50 cents apiece.