Netflix has tapped Microsoft as its first major ad tech partner as the streaming giant embarks on its plans to build an advertising business.

On Wednesday, Greg Peters, Netflix’s chief operating officer, officially named Microsoft “global advertising technology and sales partner” to Netflix.

For weeks, industry watchers expected that Netflix was close to picking an advertising platform to help it build the ad-supported tier of service. In April, Netflix announced its interest in bringing ads to a lower-priced streaming subscription package.

Read more: Why Netflix chose Microsoft

“Microsoft has the proven ability to support all our advertising needs as we together build a new ad-supported offering,” Peters said in the announcement. “More importantly, Microsoft offered the flexibility to innovate over time on both the technology and sales side, as well as strong privacy protections for our members.”

Microsoft has been developing its ad platform, including the acquisition of Xandr, an ad marketplace that ties into connected TV. Microsoft also owns LinkedIn, which has a growing ads business.

“Marketers looking to Microsoft for their advertising needs will have access to the Netflix audience and premium connected TV inventory,” said Mikhail Parakhin, Microsoft’s president of web experiences.