Ahead of next week's antitrust hearing, sources say the committee spoke with Microsoft's Brad Smith on his concerns about how Apple operates its App Store (Juli Clover/MacRumors)

Juli Clover / MacRumors:
Ahead of next week's antitrust hearing, sources say the committee spoke with Microsoft's Brad Smith on his concerns about how Apple operates its App Store  —  Apple CEO Tim Cook, Amazon CEO Jeff Bezos, Alphabet/Google CEO Sundar Pichai, and Facebook CEO Mark Zuckerberg are all set to participate …