Banks make loans or help the entity to raise debt by underwriting bond offerings, which are used for capital investment, business expansions, new pipelines etc. They’re not investing your deposits into public equities, they’re not allowed to do that.

Asset Managers are typically investing in the public equities, where they’re passive (they’re just buying whatever is in the benchmark they’re tracking) or they’re active (so they may be overweighting towards certain stocks but typically are measured against a benchmark which contains all manner of stocks).

One is an active decision to extend credit to companies to expand and invest, the other is more based on the fact that these companies exist and if you offer a product that tracks the stock market you can’t just choose to exclude companies from that. From a fiduciary perspective, it would be impossible. That’s why so many asset managers are rushing to offer personalized and thematic investment product, so the decision can lay with the individual. I.e a US equity index product but excluding companies based on GICS classifications, ESG scores, or thematic baskets.

When you divest equity, it doesn’t just cease to exist. Someone else buys it. If blackrock sold all the oil and gas stocks they own, they would simply pass into the ownership of other entities. That’s why anyone with half a brain realizes that asking asset managers to just divest from fossil stocks is pointless and most likely dangerous.

So that’s how the way that banks invest and asset managers invest is quite different. It’s reasonable to not want banks to offer credit to fossil fuel companies, that would hurt those companies, it’s downright stupid to want asset managers to simply sell the stocks of companies we don’t like. It just means that ownership stake and voice is diluted, and passed to other entities.