Mastercard's second-quarter profit rose 17% as customers kept up spending heavily via its cards, sending shares of the payments giant up 4% shortly after the opening bell.

A tight labor market has ensured job security for customers while wage growth has increased their discretionary spending power, allowing them to make purchases without restraint even as the U.S. Federal Reserve keeps monetary policy tight.

Mastercard's switched volume, which measures the value of transactions processed on its network, were 10% higher than last year.

Cross-border volume, a gauge of travel demand that tracks spending on cards outside the country of their issue, climbed 17% in the same quarter.

Commentary from payments companies is being watched closely for signs that the Federal Reserve's rate-hiking campaign is bearing fruit.

Mastercard's profit was $3.3 billion, or $3.50 per share for the three months ended June 30, compared with $2.8 billion, or $3 per share last year.

Its revenue rose 13% over last year on a currency-neutral basis, to $7 billion.