500 Pesos

The P#126 series was issued during a period when Banco de México was actively transitioning its higher denominations toward polymer substrates — the 500 Peso note remained on cotton through this run while the 50 and 20 Peso notes had already moved to plastic. Whether that decision reflected cost modeling, public resistance, or simply denomination-specific security planning was never publicly explained by the bank.

Watermarking on cotton at this face value is the minimum one would expect. The absence of more advanced features on a note of this purchasing weight is worth noting for the collector.