The line item can appear in their half-yearly or yearly results. The period of the results isn't relevant, simply that it appears in a financial statement this year. 

The reason a bank might want to do this is to show shareholders that they are taking AI seriously and that therefore shareholders can expect better returns from them.

I will evaluate this by looking through the financial statements and seeing if I can see a line that corresponds to AI spending. I am only considering Westpac, NAB, Commonwealth and ANZ. In the unlikely event that these 4 banks are no longer "the 4 major banks in Australia" by the end of the year, I will make a judgement about what are considered major banks.

It has to be explicitly labelled "AI" or "Artificial Intelligence": a budget for machine learning or digital transformation doesn't count. Also, if the AI expenditure is reported as part of a broader category, such as 'technology investments,' it will not be considered a separate line item for the purpose of this question." It can't be just for one subsidiary.

It doesn't have to be in the main financial statement, it can be in the notes or other sections, as long as it able to be identified easily by an investor. 