What happened

Shares of Sony (NYSE:SNE) 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.