HighTower Advisors Acquires New Stake in BlackRock World ex U.S. Carbon ETF HighTower Advisors LLC recently purchased nearly 6,000 shares of BlackRock World ex U.S. Carbon Transition Readiness ETF, valued at $257,000. The ETF, targeting companies outside the U.S. ready for a low-carbon shift, has attracted attention from several major investors over the past quarters, signaling growing interest in sustainable investment vehicles.34