[Insert Bank Name and Address Here]
Attn: [CEO*]
Dear [Bank Name and/or CEO],

For __ years, I have trusted [Bank Name] with the funds in my [checking/savings/etc.] account(s). Unfortunately, your bank has broken that trust.

By continuing to invest my money in the fossil fuel industry, you have destroyed my faith in your business. By underwriting the unchecked exploitation of oil, coal, and gas reserves, you’ve allowed my finances to contribute to climate change that endangers my own future and the future of all life on Earth. By condoning the land grabs of your corporate partners, you’ve made me an unwilling accomplice to the displacement of people from their homes and the destruction of their lands. By funneling cash into drills and pipelines that could have instead been invested in clean, renewable energy to power the sustained possibilities of a new green economy, you’ve proven that you lack the wisdom, foresight, and resourcefulness that you advertised.

Today, I am closing my account(s) and moving my money to a more responsible institution. While I may be just one customer out of millions, rest assured that as long as you continue to invest in the fossil fuel industry, I will continue to encourage friends, family, colleagues, and everyone else I meet to keep their assets away from your bank.
It is my sincere hope that by acting to protect the only planet we have, myself and others will help you and your bank realize the importance of acting to protect the only resource you have—your customers. Until you change your ways, you have lost this one.