What happened with the big four ASX 200 bank stocks in May?

The S&P/ASX 200 Index (ASX: XJO) gained 3.8% in May, with two of the big four ASX 200 bank stocks joining in the rally and two going backwards.

Here’s how they performed over the month just past:

• Commonwealth Bank of Australia (ASX: CBA) shares gained 5.6%
• ANZ Group…