What advice would you give to people transitioning into product marketing from less common roles like investment banking/finance?
Product marketing can be an especially hard role to break into, but not impossible! First, one of the most powerful things for a product marketer is how well they know and understand the audience they need to speak to. Look for PMM roles that are looking to sell to your current role, since you'd bring firsthand knowledge of that audience. For example, if you're in finance, you can look for PMM roles at companies selling finance products that you might use; or industry-specific PMM roles focused on financial services.
Next, good product marketers know how to work cross-functionally to deliver big impact projects and then measure the impact. When preparing your resume or for interviews, I'd recommend including some examples of leading cross-functional projects in your current role (or helping to unblock a cross-functional project even if you weren't the lead). Be prepared to talk about why it mattered, why it was (or wasn't) a success, what worked well, and what you'd change for next time.
Finally, if you're struggling to break in, try finding roles that work closely with PMM - such as customer marketing, content marketing, partner marketing. This can give you the opportunity to better build your marketing skills and get to know a certain company or industry. Sometimes it can be easier to then transition internally from there as PMM roles become available.