Scott Colbert has rarely felt the need to dig in during his four decades as a bond investor. Now, he says, is one of those times.

"Don't get too greedy," the PIMCO veteran warns as credit markets become increasingly expensive. His cautious stance reflects growing concerns about valuations in the corporate bond space.

Colbert's advice comes amid a rally in risk assets that has pushed credit spreads tighter, making yield pickup more elusive for investors seeking safety. He emphasizes the importance of patience and selectivity in navigating current market conditions.

With over 40 years of experience, Colbert's perspective carries weight among institutional investors who remember the 2008 financial crisis and other market dislocations. His warning serves as a reminder that even seasoned professionals are finding it challenging to identify attractive entry points in today's elevated credit environment.