BlackRock Inc. (BLK) turned in a fourth quarter that had Goldman Sachs analyst Alexander Blostein feeling optimistic. The asset management behemoth reported net revenues of $6.33 billion, beating Street expectations by 3%, while adjusted earnings came in at $13.16 per share, comfortably ahead of the $12.09 consensus.

Blostein, who maintains a Buy rating and $1,234 price target on the stock, highlighted what really made the quarter shine: organic base fee growth of 12%. That's the kind of number that gets investors excited because it shows BlackRock isn't just gathering assets—it's gathering the right assets.

The firm pulled in $342 billion in net flows during the quarter, translating to about 9% long-term organic growth. But here's the kicker: those flows skewed toward higher-fee products, which is why base fee growth outpaced asset growth. For the full year, organic base fee growth reached 9%, landing at the higher end of what investors were hoping for.

Looking ahead, Blostein sees BlackRock's organic base fee growth averaging north of 7%, with technology revenues likely supporting high-single-digit revenue growth and mid-teens earnings growth over the next few years.

Investors seemed to like what they heard. BlackRock shares jumped 4.64% to $1,142.51 following the results.