(Updates prices) By Bruno Federowski BRASILIA, Aug 1 (Reuters) - The Mexican peso strengthened on Wednesday amid growing optimism about the renegotiation of the North American Free Trade Agreement (NAFTA), a crucial pillar of the nation's economy. Mexican negotiators are traveling to Washington this week for another round of talks with the United States. The two countries are nearing agreement on auto content rules, which have been a sticking point in the negotiations, Mexican and Canadian officials said on Wednesday. Investors will be closely monitoring the talks in the coming days, CI Banco economist James Salazar said. "Depending on the scope of the potential agreement, the peso could even appreciate to below 18 per dollar," he said. The peso firmed 0.17 percent on Wednesday. But Mexico's benchmark stock index slipped 0.55 percent as investors continued to book profits after second-quarter earnings reports last week. In Brazil, the benchmark stock index Bovespa inched up 0.3 percent, bolstered by the banking sector's recovery. The country's real currency dipped 0.15 percent. Declining prices of basic materials weighed on shares of miners, such as Brazil's Vale SA. The Chilean peso underperformed, falling 0.89 percent as copper prices slumped due to concerns over escalating trade tensions. Latin American stock indexes and currencies at 1959 GMT: Stock indexes daily % YTD % Latest change change MSCI Emerging Markets 1086.11 -0.12 -6.13 MSCI LatAm 2694.84 -0.27 -4.45 Brazil Bovespa 79244.66 0.03 3.72 Mexico IPC 49427.05 -0.55 0.15 Chile IPSA 5406.10 -0.52 -2.85 Chile IGPA 27218.88 -0.52 -2.72 Argentina MerVal 29366.47 0.27 -2.33 Colombia IGBC 12184.83 0.4 7.16 Venezuela IBC 89611.55 0.29 6994.35 Currencies daily % YTD % change change Latest Brazil real 3.7584 -0.15 -11.84 Mexico peso 18.6150 0.17 5.82 Chile peso 642.55 -0.89 -4.34 Colombia peso 2895.85 -0.27 2.97 Peru sol 3.272 0.00 -1.07 Argentina peso (interbank) 27.5000 -0.29 -32.36 Argentina peso (parallel) 28.15 0.36 -31.69 (Reporting by Bruno Federowski; Additional reporting by Julia Love; Editing by Grant McCool and Sandra Maler)