(Bloomberg) -- Over the past year, the oil-rich emirate of Abu Dhabi has explored a string of ambitious acquisitions in the international banking sector in an attempt to become a global financial powerhouse. None have panned out so far. Most Read from BloombergThese Are World’s Most Expensive Cities for High-Class LivingNoises Detected in Search for Titanic Sub as Oxygen DwindlesHedging Failure Exposes Private Equity to Interest-Rate SurgeWhat We Know About the Missing Titanic SubmersibleTitanic