Shares of McDermott International Inc. rocketed 42% in active premarket trading Friday, after the provider of engineering and construction services to the energy industry said it was exploring the sale of its Lummus Technology business, which has been valued at more than $2.5 billion. The company said it recently received unsolicited approaches to acquire all or part of Lummus, which is a licensor of proprietary petrochemicals, refining, gasification and gas processing technologies. “The process of exploring strategic alternatives is part of our ongoing efforts intended to improve McDermott’s capital structure, and we plan to use the proceeds from any transaction involving Lummus Technology to strengthen our balance sheet,” said Chief Executive David Dickson. McDermott said it has retained Evercore as lead advisor on strategic alternatives for McDermott. The stock, which has plummeted 73% this week through Thursday amid concerns the company may be mulling a bankruptcy, has shed 92% over the past 12 months, while the SPDR Energy Select Sector ETF has lost 18.5% and the S&P 500 has gained 2.6%.Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.