A CommScope worker attending to a wireless radio installation. Photo: CommScope.

What: Shares of Commscope (NASDAQ:COMM) fell as much as 15.4% on Monday morning, following a mixed third-quarter report paired with weak forward guidance.

So what: The contractor of high-speed network installations and operations saw third-quarter sales decline 3% to $973 million. Adjusted earnings fell 15% to $0.53 per diluted share. Analysts would have settled for just $0.50 per share on the bottom line, but were also looking for revenues closer to $1.1 billion.

Looking ahead, CommScope centered its fourth-quarter revenue guidance at $1.16 billion, and non-GAAP earnings are expected to land near $0.42 per diluted share. Hitting these targets would work out to 40% year-over-year sales growth and 11% higher earnings per share, but analysts wanted more. The current analyst view calls for fourth-quarter earnings of $0.53 per share on something like $1.29 billion in top-line revenue.

Now what: The third-quarter report includes roughly one month's worth of contributions from the $3 billion all-cash buyout of TE Connectivity 's (NYSE:TEL) telecom, enterprise, and wireless operations. The buyout added $141 million to CommScope's third-quarter sales and $26 million to the $201 million in companywide operating income.

The buyout boost plus strong results in the enterprise division weren't enough to overcome plunging sales in CommScope's wireless and broadband segments. In particular, wireless sales fell 25% year over year and reported 36% lower operating earnings.

Wireless customers in several major markets held back on their infrastructure spending during the third quarter, according to CommScope's press materials. Foreign exchange rate effects only stood for a 5% sales hit.

CommScope CEO Eddie Edwards believes that the wireless weakness should be temporary:

"Although slow spending from certain North American and European wireless operators is a near-term challenge, we expect longer-term demand for our Wireless solutions to be positively affected by wireless coverage and capacity expansion in emerging markets and the increasing demand for mobile broadband in developed markets," Edwards said in a press statement.

Despite Monday's plunge, CommScope shares have gained 22% in 2015, including a quick 36% boost when the TE Connectivity transaction was announced. TE Connectivity, formerly known as Tyco Electronics, has gained a modest 4.5% over the same period.

Anders Bylund has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. 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.