Mortgage at 2.65% vs investing: pay down or invest €25,000?

Hi everyone, I’d like some input on a financial decision I’m considering. **Mortgage details:** * Remaining balance: €151,126.64 * Remaining term: 277 months (\~23 years) * Interest rate: 2.65% fixed * Monthly payment: €729.94 **Available cash:** €25,000 I’m considering three options: 1. Mortgage prepayment reducing the monthly payment 2. Mortgage prepayment reducing the remaining term 3. Investing the €25,000 long-term (index funds / ETFs / stocks) over \~23 years I already invest in an **S&P 500 ETF**, and I believe adding MSCI World would be somewhat redundant due to heavy US exposure (please correct me if I’m wrong). 👉 Main questions: * Does it make sense to prepay a mortgage at a relatively low interest rate like 2.65%? * If investing instead, which assets would best complement an S&P 500 position? * Would you split the €25,000 between mortgage prepayment and investing? If so, how? Profile: long-term horizon, medium–high risk tolerance, no short-term liquidity needs. Thanks in advance!