Regulators blocked Toronto-Dominion Bank's $13.4 billion bid to buy First Horizon over concerns about the bank's handling of suspicious customer transactions. The regulators were particularly concerned about the bank's anti-money-laundering practices and the speed at which it reported unusual transactions. The Bank Secrecy Act requires financial firms to report suspicious activity within 30 days of discovery, but TD reportedly only flagged 28 customer transactions during the period. Despite pledging to improve its anti-money-laundering policies, TD could not win regulatory approval for the deal. This is the latest in a series of regulatory and legal difficulties the bank has faced recently, including a $122 million settlement with the Consumer Financial Protection Bureau and a $1.2 billion settlement related to its involvement in a Ponzi scheme.