Banco Espírito Santo (BES) was a Portuguese bank based in Lisbon that on 4 August 2014 was split in two banks: Novo Banco, which kept its healthy operations, and a "bad bank" to keep its toxic assets.

It once was the second-largest listed Portuguese bank and the ninth-largest contributor to the PSI-20 index. BES was the second-largest private financial institution in Portugal in terms of net assets (€80,700 million in March 2011), with an average market share of 20.3% in Portugal and 2.1 million clients.

On 3 August 2014, Banco de Portugal, Portugal's central bank, announced a €4.4 billion bailout of BES that heralded the end of BES as a private bank. The bailout was funded by the Portuguese Resolution Fund (Portuguese: Fundo de Resolução). The bank was split into a healthy bank, Novo Banco, while the toxic assets remain in the existing bank.

It has since been proven that the administration of BES led by Ricardo Salgado "disobeyed the Bank of Portugal 21 times, between December 2013 and July 2014", practising "wilful acts of ruinous management"