By Utkarsh ShettiJuly 30 (Reuters) - Mastercard posted a second-quarter profit that surpassed Wall Street expectations on Thursday, boosted by robust transaction volumes driven by steady consumer spending. Mastercard's gross dollar volume - the value of all transactions processed on its platform - jumped 8% in the second quarter to $2.9 trillion. Earlier this week, peer Visa topped profit expectations for the quarter, buoyed by strong volumes from the FIFA World Cup. "Impacts from ​the instability in the Middle East moderated throughout ​the second quarter and were less severe than we anticipated," Mehra said on the ‌post-earnings call. The company's cross-border volumes, a metric ​that tracks spending on cards ​outside the country they were issued in, climbed 12% in the second quarter.