BlackRock's Mullin on a culture of 'maximum flexibility'

Stacey Mullin, deputy chief operating officer of BlackRock, during American Banker's Women in Banking Conference 2026.

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• Key insight: BlackRock's deputy chief operating officer said the key to successful leadership is being flexible but adhering to key principles.
• Expert quote: "So, no religion. Just do what's right for the clients first, the firm second, and then team and self below that. That's the foundation." — Stacey Mullin, deputy chief operating officer of BlackRock

What's the key to BlackRock's M&A success? Culture over "religion."

Stacey Mullin, the deputy chief operating officer of the $15 trillion asset manager, said the key to successful integration is for firms to commit to its "north stars" and be flexible on everything else. 

During a fireside chat at American Banker's Most Powerful Women in Banking Conference on Tuesday, Mullin said, BlackRock has two non-negotiables when it comes to on-boarding new teams. 

"One is being a fiduciary, meaning clients above all, and the other is One BlackRock, which means the firm above team or business," she said. "Those are the two main pillars, and there's no religion about anything else."

She pointed to BlackRock's acquisition of Barclays Global Investments in 2009 as a prime example of its willingness to be flexible. She said that flexibility was apparent in ways that were surface level — such as the firm's adoption of the iShares branding for its exchange traded funds — and more substantial — moving away from the bespoke approach long favored by BlackRock toward Barclays scaled approach.

"So, no religion," she said. "Just do what's right for the clients first, the firm second, and then team and self below that. That's the foundation."

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Mullin said culture is not defined by what a firm says, but rather what it does. In BlackRock's case, it can be summarized as "maximum flexibility." She said this approach helped see BlackRock through two moments of mass disruption: Brexit and COVID-19. 

In the case of Brexit, Mullin was serving as COO of Europe, the Middle East and Africa. Her approach, she said, was to identify all the potential issues and get leadership aligned behind the various potential responses but to delay action as long as possible while she awaited finality on the relevant policies.

"We wanted all optionality open for as long as humanly possible," she said.

During COVID, on the other hand, Mullin said preserving flexibility meant acting immediately. In February 2020, she and others at the company could see the damage being caused by the virus in Asia and were aware that Europe could be next. Her response was to swiftly get all of her traders set up for at-home trading — something that, heretofore, the firm did not allow — and to push for its completion even in the face of logistical complications.

The at-home rollout stalled by a shipping delay, Mullin said, putting the firm's two main pillars into conflict with one another: either the traders would be left unable to trade or they would have to go into the office to work — and risk their health in the process.

"[I said,] 'Not acceptable. Move heaven and earth. Make this happen'," she said. "When you have those north stars, and you recognize that you don't have religion about anything else — I didn't have religion about how much money it was going to cost to get those computers where they needed to be — then it's much easier."

Flexibility has also defined BlackRock's approach to the current moment of disruption: artificial intelligence. Mullin said this approach is critical given the wide range of potential outcomes from the advent of this new technology.

"It's so democratized and diffused that you have this sense of tremendous potential and real progress that actually sometimes doesn't end up doing anything," she said. "That, to me, is one of the big dangers of AI, that I don't know exactly what 'good' looks like. So, I'm going to let a thousand flowers bloom and see what happens. Maybe I'll get a tree."

Mullin said BlackRock's AI implementation has four main components. The first is to demystify the technology by getting it in everyone's hands for experimentation. To do this, the firm has given all 25,000 employees access to Microsoft Copilot — a solution she described as "low cost" with no expectation of productivity gains that accrete to the firm.

Another initiative is encouraging people to create agents to help with individual and team-level tasks. Mullin said these activities should be encouraged and celebrated, but done in as cost-effective a way as possible.

"I don't want them to spend too many tokens, and I'm not going to get that much productivity. That's okay. Still celebrate it," she said. "I want it to happen, but it's kind of like when we gave everybody Excel and it made all their discount cash flow models better."

The next layer of the AI strategy is the development of AI tools that drive commercial activity. Mullin described these as the firm's "speedboats," noting that his level of work takes up about 90% of attention on AI.

"There are six major commercial levers that I care about that I want to reimagine and transform," she said. "Those are going to make a difference to our growth and our ability to to serve more and more clients."

The final leg of BlackRock's AI strategy is a brainstorming activity, in which employers are asked to imagine how an upstart firm might use AI to disrupt incumbents in the asset management space. Once those ideas are gathered, Mullin said, BlackRock sets out to develop those capabilities for their own use.

As with other moments of disruption, Mullin said, the key to a successful AI strategy is to be prepared for any eventual outcome.

"If you don't know where you're going, every path will take you there," she said.