Bermuda-based Enstar Group has quietly amassed a run-off empire of some $10 billion in assets acquired.The company has paid out an average purchase price of about 20 cents on the dollar to acquire those assets and has to manage all the liabilities that came with them.At a time of softening rates and low interest rates, when many in the re/insurance industry have put growth on on the backburner, Enstar's growth rate is accelerating - during the second half of last year alone, it made 13 significant acquisitions.The businesses it acquires are in run-off, which means they have stopped writing new business and have to be managed to deal with their continuing obligations, particularly claims from policyholders.It's a complex business and heavily dependent on actuarial, legal, financial and claims expertise. Putting an accurate value on the companies and estimating potential future claims is key. The process of due diligence and the negotiating deals can be painstaking.That may be why there are few companies competing in the run-off acquisition space. US giants Berkshire Hathaway and National Indemnity Company are the biggest participants, but Enstar is the world's biggest company solely dedicated to run-off business.Enstar chief operating officer Paul O'Shea said in an interview in the company's third-floor office in Windsor Place, Hamilton, that the opportunities for expansion are huge.“PWC has estimated the non-life run-off market in Europe is worth about $280 billion,” Mr O'Shea said. “In the UK alone, it's $47 billion, according to KPMG. In the US, it's more than those two combined.”Companies don't only go into run off when they fold. Most run-off business comes from a line or segment being discontinued at a healthy insurer.Enstar's business exploded in 2008 when it announced 13 acquisitions for a combined purchase price of $1.12 billion. The market stalled somewhat in 2009, but the deals started to flow again in the latter part of last year.“2008 and 2010 were busy and that was reflective of the market,” Mr O'Shea said. “In 2009, there were very few deals because there was so much uncertainty after the market meltdown.”Last December, Enstar agreed to pay $200 million for Clarendon, a US specialty insurance unit that was part of the Hannover Re group. It was the biggest deal the company had done since the financial crisis and was financed by a bank loan facility and cash.When the deal closes, it is expected to take the total acquired assets of Enstar's 44 publicly announced deals to more than $10 billion.Mr O'Shea, who was one of the founders of Castlewood, along with Enstar's chief executive officer Dominic Silvester and joint COO Nick Packer, says the company's bedrock is its staff. The total workforce in Enstar's operations in Bermuda, the UK and Australia, was 331 as of November last year.“There are a very limited number of experienced run-off professionals and a large proportion of them work for us,” Mr O'Shea said. “We have a very low turnover. There are plenty of great people in the industry, but most of them want to work in live business.”Enstar's actuaries have been getting their sums right so far. The company has been profitable and has achieved remarkable growth, particularly over the last five years. Shareholders' equity grew more than 10 percent in the first nine months of 2010 to $883.2 million, a huge climb from the $261 million at the end of 2005. The company's total assets topped $5 billion as of September 30.Enstar trades on the Nasdaq Stock Exchange and has a market capitalisation of $1.07 billion.