On Wednesday, in a little-noticed move, CNN chief Mark Thompson took a consequential step that quietly telegraphed how he’s thinking about the network’s future leadership—specifically, who might be positioned to take the reins when he eventually exits. In a memo sent to staffers, which has not been reported, Thompson unveiled what he described as a “significant” move: elevating the network’s digital chief, Alex MacCallum, to chief operating officer.

"In a remarkable two year run back at CNN, Alex has already achieved an impressive set of critical accomplishments in record time," Thompson wrote. "On top of building a world-class digital operation and transforming our core products, she’s led and launched a direct-to-consumer sub business, assembled a set of outstanding leaders in audience, data, product and tech, engagement and monetization, and has built excellent collaborative working relationships with all of CNN’s other top leaders."

Thompson said that in her new role, MacCallum will take on several new responsibilities, including consumer strategy, the implementation of a new business operating model, performance tracking across the company, strategic partnerships, and “the introduction of mission-driven project work to tackle our toughest challenges.” She will, of course, continue to oversee the network’s digital products and services as well—effectively consolidating even more operational power under her already impressive purview.