The deal will create a new private capital platform with more than $60 billion in combined committed capital.
Pacific Asset Management will be renamed Aristotle Pacific Capital.
Bradley Dyslin will take over the role next year from Eric Kirsch, who is retiring.
The plan made additional commitments to existing managers at its meeting last week.
The plan is in the early stages of evaluating its long/short equity, absolute return and fixed-income credit portfolios.
The plan is looking to expand its existing $1.16 billion factor portfolio to a global all country equity mandate.
The plan committed a total of $15 million to two private equity managers this summer.
Shundrawn Thomas will lead a firm providing credit and other financial solutions to lower middle market companies.
The plan hired a new domestic small-cap growth equity manager after Voya Investment Management acquired the U.S. business of prior manager Allianz Global Investors.
The plan hired two active emerging markets equity managers to split the allocation.