Asian shares have mostly fallen, shaken by a Wall Street tumble that set off worries the biggest U.S. bank failure in nearly 15 years might have ripple effects around the world. Shares fell in Tokyo and Sydney, but were little changed in Seoul. U.S. financial regulators said before Asian trading opened that all Silicon Valley Bank clients will have access to their funds and announced steps designed to prevent more bank runs. They also said another bank had failed, New York-based Signature Bank. They are the second- and third-biggest U.S. bank failures.