This is an example of Big Government that no one (read: rich people) complains about. The Dollar/Real exchanges are done between banks in Brazil, and as such it is a small market. If the government didn’t intervene with these swaps the exchange rate would be unpredictably insane. It is not really “losing” money, its just acting as a market maker for future Dollar purchases. In terms of the values on the date the swap was created, the Central Bank has the same amount of money it started with, the “loss” is calculated because the Dollar changed value as time passed.
BC tem ganho de R$ 17,733 bi com swaps cambiais nas duas primeiras semanas de novembro
Sometimes someone will complain that the Government is manipulating the exchange rates, but that is a stretch of the truth. It is only attenuating the excesses that are due to the small exchange market and the timely spikes in demand for Dollar or Real. It keeps the speculators from taking advantage of our exporters/importers when they have a spike in foreign exchange that could move the market temporarily.
What is interesting is that the amount of Dollar in the market is entirely controlled by the Central Bank. It can add Dollars anytime it wishes, and reduce the price of the Dollar, or vice versa. It has done so during crises by negotiating swap agreements (basically loans) with the Fed that would provide it billions of Dollars as needed. All it has to do is pay the Fed an interest rate differential.

I have probably oversimplified the process a bit. See this article for a bit more detail and the history of the exchange process.

And below is a link to a very detailed article/study on the operation of the foreign exchange market in Brazil, good read:

Mercados futuro e à vista de câmbio no Brasil: o rabo abana o cachorro