iShares IV Public Limited Company - iShares US Mortgage Backed Securities UCITS ETF (BKISF.US)

iShares IV Public Limited Company - iShares US Mortgage Backed Securities UCITS ETF (BKISF.US) has delivered near-flat annualized growth of 0.1% over the last 10 years. A $10,000 investment at the start of the period would have grown to approximately $10,121, representing a total return of 1%. Over this period, BKISF.US generated positive annual returns in 3 out of 10 calendar years (29%).

The best single calendar year for BKISF.US was 2020, with a return of +11180.8%. The worst year was 2026, when the asset declined 99.0%. This spread between best and worst year is a useful indicator of the range of outcomes an investor might have experienced in a given 12-month window.

The asset's Sharpe ratio of 910.59 is considered excellent on a risk-adjusted basis. The Sharpe ratio measures return earned above the risk-free rate per unit of total volatility — a higher reading indicates more efficient return generation relative to the risk taken. Investors focused on risk-adjusted outcomes should weigh this figure alongside absolute CAGR when making allocation decisions.

BKISF.US's annualized volatility of 4476.4% is classified as high relative to the long-run US equity benchmark of approximately 15%. This above-average volatility means investors in BKISF.US have historically experienced larger day-to-day price swings than the broader market, which requires a higher tolerance for short-term portfolio fluctuations.

The asset's maximum peak-to-trough decline over the study period was 99.2% — a catastrophic peak-to-trough decline. Drawdown magnitude is a critical consideration for investors who may need to liquidate positions during market stress, as a larger decline requires proportionally greater subsequent gains to recover to the prior peak. A 99% drawdown, for example, requires a 12976% gain just to break even.

When evaluating BKISF.US for inclusion in a diversified US portfolio, it is important to note that historical volatility and drawdown metrics are backward-looking. They capture the risk environment of the past 10 years, which included the COVID-19 market crash (2020), the 2022 Federal Reserve rate hike cycle, and various geopolitical disruptions. Future risk may differ materially, particularly in response to structural changes in US monetary policy, sector regulation, or macroeconomic regime shifts.

The macroeconomic factor model attributes 39.4% of BKISF.US's return variance to Short-Term Interest Rates. This means that when Short-Term Interest Rates rises or falls sharply, BKISF.US tends to move in the same direction with meaningful magnitude. Investors who already hold significant exposure to this factor — through other funds or direct equity positions — should be aware of this concentration when sizing their BKISF.US allocation.

The second-largest macro driver is High-Yield Corporate Credit, contributing 12.8% of variance. 32.6% of BKISF.US's risk is attributable to idiosyncratic, stock-specific factors that are uncorrelated with the broader macro drivers. A higher idiosyncratic share generally indicates that the fund's performance is more dependent on the security selection or holdings composition of the individual underlying assets, rather than broad market forces.

For US investors building a diversified multi-asset portfolio, understanding BKISF.US's factor exposures helps assess its marginal contribution to overall portfolio risk. Adding BKISF.US alongside assets with low correlation to Short-Term Interest Rates — such as US Treasury bonds, commodities, or assets with significant developed-market ex-US exposure — can reduce the overall portfolio's sensitivity to any single macroeconomic theme.