SAO PAULO, Nov 14 (Reuters) - Brazilian state-run electricity utility Eletrobras posted a net loss of 915 million reais ($393.34 million) for the third quarter as it continued to adapt to government-mandated tariff reductions, according to a securities filing on Thursday.

That compares to a net profit of 1 billion reais a year earlier.

Eletrobras agreed in December to a government plan to renew expiring hydroelectric dam concessions in exchange for electricity rate cuts of between 18 percent and 32 percent.

The changes led to weak first and second-quarter profits and continued to weigh on the company in the third quarter, as net revenue dropped to 6.1 billion reais compared to 6.7 billion a year earlier.

The company is struggling to adapt to the new reality of lower rates by cutting costs and reorganizing its management structure, which is spread across a range of subsidiary companies. In mid-August the company announced it had hired Munich-based consulting firm Roland Berger to advise on its restructuring.

Earlier this year the company said it planned to spend 1.4 billion reais to cut 5,000 jobs as it embarks on a three-year turnaround effort aimed at slashing costs by 30 percent.

As part of its restructuring, Eletrobras is seeking approval from the government to sell its six distribution units, which lost a combined 1.33 billion reais for the company in 2012.

The company said severance costs weighed on its results, as well as the impact of tariff reductions.

Earnings before interest, tax, depreciation and amortization fell to a negative 436 million reais. The company did not give a comparative figure for the previous year.