As BuzzFeed was exploring plans to go public earlier this year, it ran into a problem: Executives at the digital-media outlet's biggest investor, NBCUniversal, thought they were getting a bad deal.

At issue was BuzzFeed's plan to merge with a special-purpose acquisition company, or Spac. Executives at NBCUniversal were frustrated that the deal valued BuzzFeed at $1.5bn, below the level where it had invested years earlier, people familiar with the situation said. The unit of Comcast was facing a substantial loss on the deal, while earlier investors would come out ahead.