This thesis consists of three essays that relate the currency risk management with the performance of Brazilian firms in currency crises. The first essay tests if the exchange-rate balance sheet effects of the currency depreciation reduce the companies´ investments. We find that, between 2001 and 2003, firms that shortly before the crisis had large currency mismatches decreased their investment rates by 8.1 percentual points, relatively to other public firms. Moreover, we show that the currency depreciation implied large competitive gains for the exporters, and yet the investment of exporters with large currency mismatches fell by 12.5 percentual points, relatively to other exporters. The estimated falls in investment are economically very relevant, thereby corroborating the relevance of negative exchange-rate balance sheet effects of currency depreciation. The second essay investigate if the cross-listing in the U.S., mainly through ADRs, discipline corporate decisions. Using data on the Brazilian currency crisis of 1999, we show that firms with ADRs manage their currency risk more effectively. Anticipating the crisis, ADR firms reduced the average ratio of their currency mismatches over assets by 6.4 percentage points, relatively to other public firms. Additional results link this stronger adjustment to the pressure of international arbitrageurs. Finally, the third essay tests if the government guaranties that there won´t be a large devaluation of the exchange rate, implicitly in a fixed exchange-rate regime, bias corporate borrowing towards foreign currency. Data on Brazilian firms, before and after the end of the fixed exchange rate regime in 1999, suggest that the implicit guarantees do not have a relevant impact on firms´ incentives to issue foreign debt.