iShares US Mortgage Backed Securities UCITS ETF USD (Dist) is an exchange-traded fund that tracks the performance of the Bloomberg US Mortgage Backed Securities Index, focusing on investment-grade mortgage-backed pass-through securities issued by U.S. government agencies like Fannie Mae, Freddie Mac, and Ginnie Mae. Launched on May 23, 2016, and domiciled in Ireland, it provides exposure to a diversified portfolio of over 500 agency MBS, which represent claims on cash flows from residential mortgage pools, delivering income through semi-annual distributions of principal and interest payments. Key features include a total expense ratio of 0.28%, currency unhedged in USD, and physical replication via sampling, with major holdings dominated by Federal National Mortgage Association (around 39%) and Federal Home Loan Mortgage Corporation (around 30%). Portfolio characteristics feature an average weighted maturity of approximately 6.65-7.79 years, effective duration of 5.46-5.67 years, and yield to maturity around 4.74-5.28%, managing assets between 779 million and 911 million Euros. This ETF plays a significant role in fixed income strategies, offering low correlation to equities and diversification within the U.S. MBS market.