Everyone gets diluted when a company raises more money: founders, employees, and previous investors. Investors usually have ‘prorata rights’ which mean they are allowed to invest additional money at the new valuation to maintain their given percentage ownership of the company.

Founders generally have the same class of stock as employees (common stock), and so are in the same boat.

Investors have preferred shares. Preferred shares have a few special properties, but the most important is ‘liquidation preference’, meaning they’re first in line to get their money out if things go wrong. Sometimes investors have a right to a multiple on their money back: twice their money would be a 2x liquidation preference.

One thing to ask about in the case of a company that has raised money on convertible notes. Since they haven’t actually sold equity, but only debt which will later convert equity, it’s worth asking if a given stake is before or after those notes convert.

Generally, if things are going well, dilution isn’t worth worrying about. In any case, the founder will be just as diluted as any employees, so their interests are aligned.