AT&T Inc. said on Monday it would buy online advertisement exchange company AppNexus Inc, less than a month after the No. 2 U.S. wireless carrier closed its $85 billion deal to acquire media company Time Warner Inc .

AT&T did not disclose the AppNexus deal value. However, the Wall Street Journal, citing sources, reported last week that the company was in talks to buy AppNexus for about $1.6 billion.

AppNexus, which runs a digital platform for advertisers to purchase online ads, will become part of AT&T advertising & analytics, as the U.S. telecom company aims to expand its online advertising to better compete with Alphabet Inc's Google and Facebook Inc.

AppNexus extends the advertising and analytics' footprint globally, expanding into Asia-Pacific, Australia, Europe, and Latin America, AT&T said.

The acquisition also adds to AT&T's ad-supported premium video content portfolio including Turner Networks, Audience Network, and Otter Media, the company said.

The transaction is expected to close during the third quarter of 2018.