On the heels of a 10.4% gain in April, the Commonwealth Bank of Australia (ASX: CBA) share price once more raced ahead of the benchmark index in May.

Shares in the S&P/ASX 200 Index (ASX: XJO) bank stock closed out April trading for $166.60. Defying a growing host of bearish brokers and analysts forecasting a sizeable retrace, shares finished May changing hands for $175.95 apiece.

That saw the CBA share price up 5.6% for the month, materially outpacing the 3.8% gains posted by the ASX 200 over this same time.

And Friday also represented a new all-time closing high for Australia's biggest bank stock.

In fact, May saw CommBank stock post a series of new record highs.

Here's what happened in the month just past.

CBA share price rebounds in second half of May

At market close on 13 May, the CBA share price was down 0.3% for the month.

The second half of May was a markedly different story.

The turnaround commenced on 14 May, following the release of CBA's third-quarter update for the three months to 31 March.

Amid lending volume growth and higher trading income, partly offset by two fewer days in the quarter, the bank achieved a 1% boost in operating income.

And despite fierce ongoing lending competition, CBA's net interest margin (NIM) was broadly stable. On the bottom line, the bank's cash net profit after tax (NPAT) of $2.6 billion was up 6% year on year.

"Our balance sheet settings remain strong," CBA CEO Matt Comyn said of the results. "We have maintained strong capital and provisioning levels and have successfully completed our FY 2025 funding task during the March quarter."

The CBA share price closed up 0.8% on the day.

What about the RBA interest rate cut?

There's been a lot of talk that interest rate easing from the RBA could pressure CBA and the other ASX 200 bank stocks.

And over time, we may indeed see those lower rate headwinds come into play.

But that certainly was not the case in May.

As you're likely aware, on 20 May the RBA opted to cut Australia's benchmark interest rate by 0.25%. That now sees the cash rate at 3.85%, down from 4.35% prior to the RBA's first rate cut in February.

But rather than go into a tailspin, the CBA share price closed up 0.6% on the day of the RBA rate cut announcement. And shares closed up another 1.5% the following day.

It's worth noting here that the analysts at Macquarie Group Ltd (ASX: MQG), while still not recommending CBA stock as a buy, believe the bank can weather lower rates better than the other Aussie bank stocks.

With shares edging higher this morning to $176.00 on the first trading day of June, the CBA share price is up 45.1% over the past full year, not including dividends.