The past month has seen some pretty average returns on the ASX boards.
The S&P/ASX 200 Index (ASX: XJO) has lost 0.06% since 18 October (including today's gain of 0.09% to 7,376 points at the time of writing). Not a terrible figure, one could say, but hardly inspiring.
The ASX banks certainly haven't been helping on the whole. Commonwealth Bank of Australia (ASX: CBA) shares are down more than 5% over the past month – largely on the back of the disappointing quarterly update this week.
Australia and New Zealand Banking Group Ltd (ASX: ANZ) shares have also been stuck in a funk. ANZ is also down over the past month by about 2.3%.
But Westpac Banking Corp (ASX: WBC) really takes the cake for 'the ASX's most disappointing bank' over the past month. Westpac shares have given up a nasty 13% since 18 October.
That leaves us with National Australia Bank Ltd (ASX: NAB) out of the big 4 ASX banking shares.
NAB has given investors a slight loss of 0.38% over the past month. This makes NAB the best performing ASX bank, even if it didn't outperform the ASX 200.
NAB has also reset its 52-week high a few times over the month. Last Friday the NAB share price hit $30.30, which is its highest level since 2018.
So, what's made NAB the best ASX bank share to have held for the past month?
NAB share price rises as dividend doubles
Well, there have been a few developments on NAB's front over the period. Firstly, we had this bank deliver its full-year earnings report for FY21 on 9 November.
As my Fool colleague James covered at the time, NAB reported a 76.8% increase in cash earnings to $6.56 billion.
This included an 0.3% bump in the cash earnings of its business and private banking segment, as well as a 14.8% drop in the cash earnings of its corporate and institutional banking division.
But perhaps most relevant for NAB investors, the bank also raised its final dividend for FY21 to 67 cents per share fully franked.
That brought its full-year dividends to $1.27 per share, a whopping 112% increase on FY20's Covid-battered payout of 60 cents per share.
That brings NAB's trailing dividend yield to 4.4% (6.29% grossed-up with full franking) at the current NAB share price.
Further, NAB has also been the beneficiary of some bullish broker notes.
Last week, investment bank and broker Goldman Sachs reiterated its buy recommendation for NAB shares.
Goldman also bumped its 12-month share price target from $30.84 to $31.15. That implies a future potential upside of just over 8% for the coming 12 months, not including NAB's meaty dividend.
Goldman likes NAB the most out of the ASX banks right now. This is due to the fruits of NAB's cost management initiatives, as well as its dominance in the business banking space.
This, Goldman predicts, will allow NAB to "benefit more from the continued economic recovery".
It's probably a combination of these factors that has helped NAB shares outperform the other big 4 ASX banks over the past month.
At the current NAB share price, this ASX bank has a market capitalisation of $94.7 billion.
