Deutsche Bank AG racked up a loss of $1.6 billion over nearly a decade on a complex municipal-bond investment that it bought in the runup to the 2008 financial crisis, and failed to confront head-on even as markets were upended and regulations tightened.

The loss, which hasn’t previously been reported, represents one of Deutsche Bank’s largest ever from a single wager—roughly quadruple its entire 2018 profit—and ranks as one of the banking industry’s biggest soured bets in the last decade.

The prolonged struggle over how to handle the investment sheds light on cultural and financial challenges inside one of Europe’s biggest banks that have hampered its ability to compete with stronger U.S. rivals.

Deutsche Bank resisted for years reducing the value of those bonds and related derivatives on its books to a level that markets suggested they were worth, and it brushed aside concerns raised by the bank’s financial auditors about how it was valuing the trade, according to internal bank documents and people involved in discussions about the investment.

During that time period, the bank was telling investors its internal financial controls were sound, and it raised billions of dollars in the capital markets without any disclosure of the bond valuation issue. Behind the scenes, the badly timed bet exerted a sustained drag on the bank’s finances.