What: Shares of Sierra Wireless (NASDAQ:SWIR)(TSX:SW) fell more than 23% early Friday after the Internet of Things pure play released weaker-than-expected fourth-quarter 2015 results and disappointing guidance.

So what: Quarterly revenue fell 2.8% year over year to $144.8 million, driven by a 2.8% decline at its core OEM segment, a 15.3% drop from enterprise solutions, and $6.8 million in revenue from cloud and connectivity services -- the last of which includes revenue from three managed connectivity acquisitions last year and was formerly rolled into the enterprise solutions segment results before Oct. 1, 2015.

Meanwhile, adjusted earnings before interest, taxes, depreciation, and amortization fell more than 50% to $6.3 million, and adjusted net income dropped more than 70% to $2.5 million, or $0.08 per diluted share.

For perspective, Sierra Wireless' own guidance called for higher revenue of $148 million to $151 million. And analysts, on average, were anticipating higher adjusted earnings of $0.10 per share on revenue of $149.4 million.

"In the fourth quarter of 2015, our revenue was slightly below expectations," said CEO Jason Cohenour, "as we experienced softer demand at select OEM customers. We believe this reflects increased caution on the part of some customers in the face of an uncertain macro-economic environment."

That said, Sierra Wireless also revealed it has received approval from the Toronto Stock Exchange of its "Notice of Intention to Make a Normal Course Issuer Bid." This is essentially a controlled repurchase authorization under which Sierra Wireless can buy back and retire as much as 22,269 common shares each day -- representing roughly 25% of the average daily trading volume over the past six months -- up to a total of 3,149,199 shares. That's equivalent to 9.7% of common shares outstanding, and 10% of the public float.

Now what: But combined with its underperformance in Q4, that wasn't enough to take away the sting of Sierra Wireless' guidance. For the current quarter, Sierra Wireless anticipates revenue of $135 million to $145 million and adjusted earnings per share to be "slightly negative to slightly positive." By contrast, analysts' consensus estimates predicted first-quarter earnings per share would decline roughly 32% to $0.15, while revenue was expected to rise 3.2% to $155.2 million.

At the same time, Cohenour noted that despite the slow start in the first quarter, Sierra Wireless anticipates its business to gain strength as the year progresses. So for the full year, it expects revenue of $630 million to $670 million and adjusted earnings of $0.60 to $0.90.

However, Wall Street was looking for earnings of $1.00 per share on revenue of $674.7 million. In the end, though the latter part of the year might well see it return to the market's good graces, it's no surprise shares are falling today given Sierra Wireless continued underperformance.

Steve Symington has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Sierra Wireless. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.