Cancer drug specialist Exelixis (EXEL 5.02%) was quite the stock market star on Friday. Following news that it's making a big, shareholder-pleasing move, market players piled into the company to push its shares 5% higher on the day. This provided some light in what was generally a gloomy trading session, with the S&P 500 index falling by 1.7%.

A $500 million move

After market close on Thursday, Exelixis announced that it will launch a new share repurchase program, authorized for up to $500 million worth of its common stock before this coming Dec. 31. This will kick in once the current buyback program, also capped at $500 million, is exhausted. The company anticipates that will occur in this year's second calendar quarter.

As with most repurchase programs, this one will take place from time to time and involve various amounts.

The new initiative will be Exelixis's fourth; the previous one was launched in August 2024. The pharmaceutical company is hardly a slacker when it comes to snapping up its own stock; the company revealed that it expended more than $1.2 billion on the activity through the end of 2024.

This doesn't fully justify owning the stock, but...

Investors tend to welcome news of stock repurchases because they mean that a company is helping prop up the value of its equity by dipping into the market for it now and again. While a buyback program should never be the leading reason for buying any stock, it is an encouraging sign that a management team has that sort of commitment.