Investors is the plural for investor. Investor’s is the singular possessive form of investor. Investors’ is the plural possessive form of Investors.
Investors or investor’s or investors’ are all pronounced the same way.
We use Investors when we want to make the word “investor” plural.
So it is:
I need one investor.
I need two investors.
Investor’s is the singular possessive form of investor. We use the possessive form of investor when we want to show that one investor owns something.
This is the investor’s portfolio.
An investor’s best strategy is to buy the dip.
Remember we are talking about only one Investor.
Investors’ is the plural possessive form of investors. When the noun already ends in “s” and we want to make the word possessive, we need to put the apostrophe after the “s”
The investors’ are having a meeting upstairs.
It can be difficult to know whether you are talking about one investor or many investors in the possessive because investor’s and investors’ sound exactly the same in spoken English.