In this case it's pretty easy to see, as the quantity is so...

In this case it's pretty easy to see, as the quantity is so small, even if all those shares were sold at once, they would have an insignificant effect on the share price.

In general, it depends on what the shareholders do. If it is directors holding who sell, it can be very bad for the share price when that is announced.
Also if it is previous, private equity owners, they often take the opportunity over time to liquidate their holding when the share price increases.

In many cases, it is the founders of the company who are still involved in the company and continue to hold, so no impact on the share price.