"I think they want to make sure all their I's are dotted and their T's are crossed, so they can say they're bending over backwards to keep all the regulatory bodies involved," said John Byrne, an analyst at Technology Business Research.
While the deal only affects the U.S. and Canada, European companies advertising in the US will be affected by it, Byrne said.
Byrne said he's not sure if any other major companies have taken a similar approach, but he said Yahoo's move seem "unique."
Paul Cuomo, an antitrust attorney at Howrey, agreed that it is unusual for a company to notify a regulatory body that doesn't have a direct impact on its business dealings. However, Cuomo said the situation is also unusual.
"The thing that's interesting is that it's so high profile, and I'm assuming the last thing Google and Yahoo, particularly Yahoo, want is any antitrust authority anywhere sticking its nose in and saying, 'We have a problem with what you're trying to do with Google,'" he said.
Even though there's no direct relationship in Europe today, the EC could be interested because there could be a spillover effect from the deal, where parties are working together in Area A, and are still competing in Area B, and there is the potential for the work in Area A to improperly affect competition in Area B, Cuomo said.
"I would expect that there's probably some anticipation by the European community antitrust authorities, who have been very interested in Microsoft, that this proposed transaction may not be the final transaction that reflects where Yahoo ends up at the end of the day," said C. Evan Stewart, an antitrust attorney at Zuckerman Spaeder. "Wherever Yahoo ends up, there's going to be scrutiny by antitrust regulators, and I guess Yahoo just thinks they should have the [EC] involved sooner rather than later."