(Adds details on intervention, chart) BRASILIA, Dec 28 (Reuters) - Brazil’s central bank intervened in the spot foreign exchange market on Monday for the first time in two months, selling $530 million after the local currency had slipped to a one-month low against the U.S. dollar . The intervention in typically illiquid year-end trading occurred after the real had fallen below 5.31 per dollar, a slide of more than 2% which had put it on course for its steepest one-day depreciation in three months. The sale helped the real claw back about half of its earlier losses to trade around 5.27 per dollar. Policymakers had said last month the central bank would intervene if the market was unable to absorb outflows related to local banks unwinding their so-called overhedge trades put on to protect their FX exposure on overseas equity investments by Dec. 31 for tax purposes. Central bank director Bruno Serra said on Nov. 18 that this total exposure stood at just under $30 billion, half of which was to be unwound by the end of the year. This was the central bank’s first spot market intervention since Oct. 30, although it has sold dollars in the repo market in the last couple of months. The real has fallen 30% against the dollar this year, making it one of the worst-performing currencies in the world against the greenback. The main drivers have been Brazilian interest rates being slashed to a record low 2.00% and growing concern about the country’s fiscal health. The real made a potentially significant technical upside break a month ago when the dollar fell below its 200-day moving average and slid toward the 5.00 reais level. But that momentum faded, and has now reversed.