Ambev SA shares posted their biggest rally since 1999 after stronger-than-expected beer volumes in Brazil drove first-quarter earnings that topped analyst estimates. The Brazilian unit of Anheuser-Busch InBev NV saw investor enthusiasm surge as volume growth in its home market exceeded Wall Street expectations.

The results signal resilience in Brazil's beer market despite economic headwinds facing the region. A beat on earnings in the company's core market can have outsized impact on Ambev's financial performance given Brazil represents the vast majority of its revenue base. The stock's reaction reflects how closely investors track volume trends in the South American nation.

The nearly 27-year high in share gains marks a rare milestone for the brewing giant. The market's response underscores confidence in Ambev's ability to deliver solid earnings from its domestic operations, potentially providing a lift to parent company AB InBev's overall results.