Can a minority share purchase leave me exposed to the same risks as buying it all?

In terms of what you personally owe, no — as a minority shareholder, your personal liability is generally limited to what you paid for your shares, and you don't become personally responsible for the corporation's debts just by holding a smaller stake. But in terms of what your investment is worth, yes: the same liabilities, lawsuits, or problems affecting the corporation affect the value of every share, including yours, whether you own 5% or 100%.

The nuance is control. A full buyer can usually negotiate broad representations, warranties, and indemnities from the seller, and can act unilaterally afterward to manage a problem that surfaces. A minority buyer often has less negotiating leverage for that same protection, and no ability to unilaterally decide how the company responds to an inherited issue — you're relying on whoever does control it.

Before buying a minority stake, it's worth having a business lawyer review what protections you can actually get in the purchase agreement, and what rights a shareholders' agreement gives you to information and input, since a smaller stake usually means less power to manage the very risks you're still exposed to.