The Westpac Banking Corp (ASX: WBC) share price had an alright year in 2021.
Its stock gained a respectable 10.22%. That's only just behind the performance of the S&P/ASX 200 Index (ASX: XJO), which rose 13%. However, all its big banking peers' stock outperformed that of Westpac.
The share price of National Australia Bank Ltd. (ASX: NAB) led the way, gaining 27% last year.
Meanwhile, those of Commonwealth Bank of Australia (ASX: CBA) and Australia and New Zealand Banking Group Ltd (ASX: ANZ) increased 23% and 21% respectively.
That leaves Westpac with less than half the gains of its worst performing peer. What could have weighed so heavily on the bank's stock in 2021? Let's take a look.
Why did the Westpac share price underperform last year?
The Westpac share price performed remarkably well for much of 2021. Between the end of 2020 and 29 October 2021, the bank's stock gained 32.5%.
Unfortunately, it figuratively fell off the cliff in November, tumbling 20% that month.
As The Motley Fool Australia reported at the time, the slump was likely spurred by the release of its full year results on 1 November.
The market was seemingly unimpressed by Westpac's performance during financial year 2021.
That was despite the bank recording a 138% lift in statutory net profit and a 105% increase in cash earnings.
Westpac's stock sank 7% on the day its results were released, and it continued to slide until the beginning of December.
From then, it staged a slight resurgence, gaining 4% over the final month of 2021. Though, that wasn't enough to push the Westpac share price back into its big bank peers' league.
Interestingly, the CBA share price followed a similar trajectory through November and December.
It fell nearly 11% in November, mostly due to the release of a quarterly update. Luckily, it outperformed the Westpac share price last month, gaining 8%.
