This Practice Note considers the risks for lenders and corporate borrowers of ignoring an event of default under an unregulated corporate or commercial facility agreement, including the potential impact on enforcement rights. It explains how lender conduct may give rise to waiver or estoppel and outlines practical steps for managing a default, including reservation of rights, waivers, amendments and standstills. Quick summary • An event of default is a contractual trigger in a finance document that allows the lender to take specified action against the borrower, such as cancelling commitments, accelerating the loan, demanding repayment, enforcing security and charging default interest. • For the lender, the key risk in not taking formal action promptly following an event of default is that its conduct may result in it waiving, or becoming estopped from exercising, rights arising from the event of default. No waiver clauses and reservation of rights letters may reduce the risk, but their effectiveness depends on their wording and the lender’s subsequent conduct. • For the borrower, lender inaction does not necessarily