General Electric Co. has this month come top of the Institutional Investor listings for the biggest single mandate, for $15,800 million. The fund hired Fidelity Investments to provide record-keeping and administration services for its Savings & Security 401(k) plan. The asset size for the plan was not immediately available.

The busiest fund is without a doubt the Pennsylvania Public School Employees Retirement System, handing out mandates worth a combined $15,500 million spread out over five mandates. The plan has committed $500 million to Sankaty Advisors, which will be run in a loan managed account. The plan has also committed $350 million to Brevan Howard Asset...