(Recasts to add share performance, comments, details on earnings throughout)
By Guillermo Parra-Bernal and Alberto Alerigi Jr
SAO PAULO, Nov 13 (Reuters) - Shares in Cia Siderúrgica Nacional SA sank the most in a month on Friday, as management failed to assuage mounting concerns over a swelling debt burden at Brazil's second-largest listed maker of flat steel.
Executives led by Chief Executive Officer Benjamin Steinbruch told investors on a conference call to discuss third-quarter results that keeping capital spending near current levels is needed to stay competitive in steelmaking and mining.
CSN, as the company is known, is pushing ahead with plans to refinance debt, sell assets, but avoid fire-sales, and raise the price of some flat-steel products. Steinbruch has likened his choices to "war economy decisions."
Investments planned for next year will add value for shareholders in the medium term, Steinbruch said.
Net debt rose to a record 6.6 times 12-month trailing operational earnings last quarter. That is twice CSN's 3.4 net debt to EBITDA ratio a year earlier. Investors are uneasy about capital spending and working capital trends, which have further eroded CSN's already weakened balance sheet, said Leonardo Correa, an analyst with Banco BTG Pactual.
Dividend payments will resume next year, pending the outcome of some aspects like asset sales, Steinbruch noted.
Shares extended losses during the call, falling as much as 9 percent to 4.92 reais. The stock has shed 50 percent over the past six months.
The price on CSN's 7 percent perpetual bond was unchanged at 45 cents on the dollar on Friday. The bond has fallen from about 75 cents at the start of the year.
"For now, the case has become very much an event-driven story, with leverage rising and depending on billions of asset sales," Correa said.
CSN's net loss reached 532.7 million reais ($140 million) last quarter, compared with a shortfall of 250.1 million reais a year ago. The result, however, was smaller than the loss of 709 million reais estimated in a Reuters poll.
More than 20 companies have shown preliminary interest in Sepetiba Tecon SA, a container terminal operator that CSN recently put up for sale, Chief Financial Officer Paulo Caffarelli said on the call.
$1 = 3.8416 Brazilian reais Editing by Chizu Nomiyama and Meredith Mazzilli