The prepositions “with”, “at” and “for” are also used to associate a business title with a company's name. It seems that they are interchangeable, with no (significant) difference in meaning. The following examples taken from The New York Times website seem to confirm that:
Until now, said Justin Nielson, a senior analyst for the media research firm SNL Kagan, “there really hasn't been any direct competitor . . .
“The consumer is still deleveraging,” said Jason Goldberg, a senior analyst with Barclays. “It's not a lack of supply; it's a lack of demand.”
“There’s the party of fear and the party of despair,” Nikos Xydakis, a political analyst and an editor at Kathimerini daily, said.
Are they really the same as for meaning? If it isn't so, what is the difference between them?