Having a CTO and SVP axed in the same statement means rather specific circumstances. Realistically rules out harassment, performance, even "kickbacks". These you would only expect one or the other to be terminated. Whether you agree or not, a company does not want to terminate immediately (she was just on stage as key speaker) two such key positions at the same time in the same department. It's a very large gap in the org that represents a material risk to the business. So their actions have to be so "huge" to match.

Stealing, but more likely some form of colluded insider trading.

I'd wager that the SVP was helping perform trades of expedia stock on behalf of the CTO. They got caught before the SEC and were fired.