National Australia Bank Ltd (ASX: NAB) shares have lagged behind their ASX banking peers these past 12 months.

Whereas the S&P/ASX 200 Banks Index (ASX: XBK) has rallied 37% in the past year, the National Australia Bank share price has clipped a 32% return.

Whilst it's not the Persian Gulf, it's still a wide enough performance gap worthy of a Sherlock Holmes-like analysis. "Watson, assemble the charts!"

Now the question remains: Are National Australia Bank shares a buy, or do other options offer better value? Let's see what the experts say.

Brokers are mixed on NAB shares

There's certainly no conviction to the upside for NAB shares. According to CommSec, two analysts rate it a buy, versus five holds and 9 sell ratings.

The bank also paid an annual dividend of $1.67 per share in FY23, and CommSec forecasts a modest increase to $1.68 per share for FY24, then $1.75 the year after.

If correct, shareholders could also expect a final dividend of 84 cents with the FY24 results.

Whilst many are bearish on the stock, NAB reportedly hired consulting firm Bain to advise on its strategy path. According to The Australian Financial Review, the bank's leaders are said to be involved.

UBS is one of the brokers bearish on the stock. It's set a price target of $32 on NAB shares, implying a 17% decline from the current level.

The broker cites National Australia Bank's recent financial performance as its basis. It notes that third-quarter revenue benefitted from a steady net interest margin (NIM), although non-interest income fell short of expectations.

For FY25, UBS forecasts NAB's earnings per share (EPS) at $2.23.

NAB trades on a price-to-earnings (P/E) ratio of 16.7 times at the time of writing, and consensus expects EPS of $2.48.

Therefore, based on its forecasts, UBS expects a contraction in the P/E multiple to 14 times (14 x $2.23 = $32).

Goldman Sachs, whilst slightly more optimistic, is also bearish on the stock. It sees potential downsides in market value as well, with a price target of $34.24, suggesting an 11% potential drop.

Goldman appreciates the bank's focus on small and medium-sized enterprises, which it believes supports better NIM management compared to retail lending.

However, it warns that sustaining NAB's current productivity gains may become challenging over time.

Foolish takeout

NAB shares have underperformed compared to other ASX bank stocks this year. Naturally, investors are questioning whether this presents a buying opportunity or a warning signal.

National Australia Bank will release its FY24 results on 7 November. The stock is up 25% this year.