An SEC filing for the UBS Series Funds explains, "The purpose of this supplement to the prospectus and SAI for UBS Select Prime Investor Fund, UBS Select Government Investor Fund, UBS Select Treasury Investor Fund, and UBS Select ESG Prime Investor Fund, each a series of UBS Series Funds, is to notify you that, at the recommendation of UBS Asset Management (​Americas) Inc., the funds' administrator, the Board of Trustees of the Trust approved Agreements and Plans of Reorganization providing for the acquisition of the assets and liabilities of each fund by its respective '​Acquiring Fund,' as set out in the below chart, each also a series of the Trust. The Agreements and Plans of Reorganization set forth the terms by which each of the funds will transfer its assets and liabilities in exchange for shares of the respective Acquiring Fund, followed by the distribution of shares of the Acquiring Fund to the shareholders of each respective fund and the complete liquidation of each fund (​collectively, the '​Reorganizations'). Each Acquiring Fund has an identical investment objective and investment strategy to that of each respective fund." The filing shows that the UBS Select Prime Investor Fund merged into the UBS Select Prime Institutional Fund, the UBS Select Government Investor Fund merged into the UBS Select Government Institutional Fund, the UBS Select Treasury Investor Fund merged into the UBS Select Treasury Institutional Fund and the UBS Select ESG Prime Investor Fund merged into the UBS Select ESG Prime Institutional Fund. UBS adds, "After the Reorganizations are consummated, shareholders of each of the funds will become shareholders of the respective Acquiring Fund. The Reorganizations are intended to be tax-​free, meaning that shareholders of each of the …