S&P Global Ratings assigned its 'AAA' long-term rating to the Economic Development Authority of Loudon County, Va.'s series 2019A bonds, issued for Howard Hughes Medical Institute (HHMI), Md. S&P Global Ratings also affirmed its 'AAA/A-1+' dual rating on Loudoun County Industrial Development Authority, Va.'s series 2013A multimodal tax-exempt revenue bonds, series 2003A-F variable rate bonds, and 2009B variable rate bonds, issued for HHMI. S&P Global Ratings also affirmed its 'AAA/A-1+' rating on Maryland Economic Development Corp.'s series 2008A and 2008B multimodal revenue bonds issued for HHMI. The outlook is stable. The 'AAA' long-term rating reflects our view of HHMI's exceptionally strong balance sheet, sound and successful investment policy, significant operating flexibility, and a governance and management philosophy of adjusting spending