Went through the full BlackRock onsite earlier this year, including two behavioral rounds. I'm also a new manager who's been on the other side of behavioral screens at my current job, so I paid close attention to what they were actually trying to measure.
First, some context on BlackRock's culture. They publish what they call their "Principles" publicly: fiduciary duty, fact-based decision making, one BlackRock. These aren't window dressing. The behavioral questions are mapped to them pretty directly, even if the interviewer doesn't say so explicitly.
Questions that came up (paraphrased): Tell me about a time you had to act on incomplete information. What did you do, and how did it turn out? Describe a situation where you had to influence a decision you didn't have direct authority over. Give an example of catching a significant error before it reached a client or customer. Tell me about a time a project you owned didn't go as planned. What happened and what did you learn? How do you approach prioritization when multiple stakeholders have competing urgent needs?
A few things I noticed about how they listened:
They interrupted more than I expected. Not rudely, but they'd stop me mid-STAR and ask a follow-up like "what were you personally responsible for vs. what did the team do?" They care about individual contribution vs. group outcomes. If you say "we" a lot, expect a drill-down.
Error and risk examples land well. BlackRock manages trillions in assets. They take risk management seriously. Saying "I caught a bug before it hit production" plays better here than at a startup.
The "one BlackRock" principle shows up as questions about cross-team collaboration. They want to hear that you've worked across silos and know how to align people who don't report to you.
I don't know yet if I got the offer (still waiting). But the behavioral rounds felt like the most substantive at any firm I've interviewed at in the past few years. They weren't going through the motions.