* Greek polls show pro-bailout parties regaining lead
* Bovespa rises 1.38 pct, Mexico IPC up 0.42 pct
By Rachel Uranga and Danielle Assalve
MEXICO CITY/SAO PAULO, May 28 (Reuters) - Latin American stocks advanced on Monday as investor fears eased over a possible disorderly Greek exit from the euro, but trading was thin with U.S. stock exchanges on holiday.
The MSCI Latin American stock index rose for a third consecutive session, adding 1.44 percent to 3441.44 but moves were exaggerated by the light volume.
Five polls published over the weekend showed conservative Greek parties backing a European bailout now have a lead in the country's June 17 elections. Fears that a new Greek political leadership would abandon bailout agreements with the European Union and International Monetary Fund sparked a recent selloff in riskier assets on fears of a messy Greek default and the country's eventual exit from the euro zone.
"There is optimism over the elections based on the advances that we saw in the polls," said Carlos Hermosillo, an analyst with Banorte-IXE in Mexico City. "But we still have to see what happens with the electoral process. There are still three weeks left to the (Greek) elections and we are going to see volatility in the market during this time."
Brazil's benchmark Bovespa stock index posted its biggest daily gain in a week, rising 1.38 percent to 55,212.69. But it was the lowest trading volume recorded this year.
Shares of PDG Realty, Brazil's largest homebuilder, gained 5 percent, contributing most to the index's rise, after Brazilian private-equity firm Vinci Partners proposed investing 799.98 million reais ($404 million) in the company, according to a securities filing on Monday.
Rival construction firms MRV Engenharia and Gafisa gained 2.52 and 2.16 percent, respectively.
"The proposal by Vinci is livening up a sector that had fallen quite a bit," said Luiz Gustavo Pereira, a strategist with Futura Corretora in Sao Paulo, though he didn't see today's performance indicating a shift in the long-term outlook for homebuilders.
That sentiment was echoed by other analysts, who said poor earnings results and difficulty securing credit would continue to weigh on the sector.
Preferred shares of Vale, the world's largest iron ore miner, gained 1.04 percent, while those of state-controlled oil producer Petrobras added 0.80 percent.
Petrobras expects to complete the bulk of a $13.6 billion asset-sale plan by the end of the year, helping to finance $225 billion of investments under its five-year corporate spending program, the world's largest, its chief financial officer told the Reuters Latin America Investment Summit.
Grupo Pão de Açúcar, Brazil's largest diversified retailer, lost 1.63 percent after the company named a new chief financial officer on Monday.
Mexico's IPC index posted its biggest daily gain in a week, adding 0.42 percent to 37,642.80.
Bottler Femsa advanced 1.19 percent and copper miner and railroad operator Grupo Mexico gained 1.0 percent.
Chile's IPSA index was up 0.14 percent at 4260.62. Shares of airline Lan gained 2.69 percent, while retailer Falabella added 0.80 percent.