What happened

Shares of Sony (NYSE:SONY) stock closed down 9.3% on Friday after the Japanese electronics giant released its fiscal 2017 year-end results (for the year ended March 31).

And yet, Sony reported year over year sales growth of 12% for fiscal 2017 -- $77 billion -- and $6.6 billion in operating profit, which The Wall Street Journal described as a new "record" for the company.

Cartoon figure pointing at a stock chart going up

You see, Sony, most investors prefer it when earnings keep going up. Image source: Getty Images.

So what

In fact, operating profits at Sony were up 154% year over year, and net income rocketed to $3.42 per share. So why might investors have been disappointed with such fabulous numbers?

Perhaps it's because while the year as a whole was terrific, the fourth quarter ... wasn't. Analysts had told investors to expect Sony would report sales of $19.6 billion in its fiscal fourth quarter, and lose only $0.02 per share. Instead, Sony reported sales of only $18 billion, and a $0.12-per-share loss.

Now what

Guidance may have been another drag on Sony shares today. Forecasting fiscal-year 2018 consolidated results, Sony told investors they could expect to see sales slide this 3% this year (which implies sales of perhaps $74.8 billion, well below analyst forecasts for revenue of $81.8 billion). Profits could decline even faster. Sony is forecasting an 8.8% decline in operating income, implying that number will come in at $6 billion.

When you consider that analysts surveyed by S&P Global Market Intelligence have been predicting long-term annual earnings growth of 90% or better for Sony over the next five years, the company's own forecast must have taken investors by surprise.

No wonder the shares are down.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.