Adobe is nearing an acquisition of marketing software company Marketo for around $5 billion, according to people familiar with the matter. (Later on Thursday, the company officially announced the deal for $4.75 billion: Full story here.)

The companies are in the final stages of reaching a deal, said the people, who asked not to be named because the negotiations are private. An announcement could happen Thursday or Friday, the people said.

Vista Equity Partners, a private equity firm that specializes in software and technology, acquired Marketo for about $1.8 billion in 2016. Adobe and Microsoft were both considering buying Marketo in 2016, sources said, but ultimately Vista won it.

The transaction helps validate Vista's strategy of buying higher-growth software companies such as Marketo. Reuters first reported Adobe was in talks to buy Marketo earlier this month.