AT&T warned investors on Wednesday that its third-quarter revenue could come in below analysts' expectations.
The telecom giant is set report earnings results on Thursday after the closing bell.
The company said that because analysts failed to appropriately factor in the company's acquisition of DirecTV in July of this year, the estimates were "inflated."
Shares of AT&T were mostly flat in extended-hours trade on Wednesday.
"With our DirecTV merger having closed on July 24, 2015, we want to make an important clarification for investors heading into our earnings announcement on Thursday," an AT&T spokesman said, in a statement. "It is clear many revenue estimates for DirecTV include the full month of July."
The company noted that the "inflated" estimates were a "one-time variance as analysts sort through some of the normal modeling of an acquisition."
AT&T said in September that it would change the methodology DirecTV used to count its commercial subscribers to conform to its practices, which would reduce DirecTV's total subscriber count by 918,600 at the close of the deal.
— Reuters contributed to this report.