SAN FRANCISCO: Apple has ceased to disclose exactly how much it spends on advertising and that has prompted financial analysts to speculate about the reason.

According to Business Insider, financial experts at Wells Fargo have spotted that the technology giant's latest 10-K annual report, which was filed with the Securities and Exchange Commission in October, did not reveal its advertising expenditure for 2016.

That contrasted with previous years – for example, Apple reported in its 10-K report for last year that it had increased its adspend by 50% to a record $1.8bn.

Instead, this year, Apple noted that its advertising costs have been placed in the less specific category of "selling, general and administrative (SG&A) expenses".

Interestingly, Apple's SG&A costs were down 1% year-on-year to $14.1bn whereas in 2015 that figure, which includes staff salaries, had increased 19% year-on-year.

According to Apple: "The decrease in selling, general and administrative expense in 2016 compared to 2015 was due primarily to lower discretionary expenditures and advertising costs, partially offset by an increase in headcount and related expenses."

However, Wells Fargo pointed out that Apple's expenses as a percentage of total net sales were actually up one percentage point to 7% and that the company ended 2016 with its lowest operating margin since 2009.

As reported by Business Insider, this could be in part due to Apple seeing less leverage – or, in other words, spending more ad dollars to drive total revenue.

While speculative, that would suggest Apple, which is not obliged to split out its adspend from its general SG&A expenses, would prefer not to show that it is spending more to maintain sales. Apple did not respond to Business Insider when asked to comment.

Data sourced from Business Insider; additional content by Warc staff