US President-elect Donald Trump did not invite Twitter CEO Jack Dorsey to his highly anticipated meeting with technology executives on Wednesday.

Trump's move to leave Twitter off the invitation list was met with a surprise by many in the industry given the fact that he used the social media platform prolifically during his election campaign.

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A Trump team spokesperson reportedly said that Twitter  was not invited because it is not "big enough."

What the Trump spokesperson means by "big enough" might be market capitalization (Twitter, standing at $13.85 billion, is smaller than Facebook and Amazon). However, one source familiar with Trump's relationship with Twitter said the decision to exclude Twitter CEO Jack Dorsey was motivated by the president-elect's unapproval of the company for rejecting an advertising deal with his campaign team in October.

Trump's campaign team had come up with an idea of having a Hilary Clinton emoticon on the social media platform and had offered to pay Twitter to show it whenever tweets including the phrase "#CrookedHillary" came up during the Presidential election. However, Twitter rejected the deal, saying it might mislead users who would not be able to tell that the emoticon was paid by the campaign.

However, a Trump transition spokesman said that the emoticon had nothing to do with the invitation omission. The spokesperson noted that the president-elect has had public spats with many other tech leaders as well like Amazon CEO Jeff Bezos and Apple CEO Tim Cook, and yet they were invited.

The smallest company in attendance was electric car maker Tesla, with a market capitalization of $31.92 billion.

Needless to say, Twitter played a huge role in Trump's campaign by helping him reach millions of his followers. During the Obama administration, Twitter was a regular participant in meetings to address technology concerns, especially since the platform is constantly used by terrorist groups and for online bullying.

Trump's team have refused to mention the names of the companies that wanted to be present in the meeting, including Twitter.