Share dilution is an important concept for any investor to understand. While revenue and profits are key, what ultimately counts is the value on a per-share basis. That's where share dilution comes in. The number of shares outstanding for publicly traded companies tends to vary from quarter to quarter, depending on whether a company repurchases shares or dilutes existing shareholders.

How share dilution affects investors
Although you should know how share dilution can sap value from your portfolio, you should also be aware of the opposite effect: share reduction. Companies can reduce their shares outstanding through share buybacks, a form of returning capital to shareholders that will make individual holdings worth more by raising per-share earnings. Some companies have a long track record of repurchasing shares, which helps them grow earnings per share over time.
Share dilution isn't always a bad thing. Sometimes, a well-timed secondary offering makes sense and can drive long-term value for a company by raising cash to expand or take advantage of a new opportunity.
Similarly, share-based compensation isn't necessarily bad either, but investors should be aware of how much dilution it's causing and how fast shares outstanding is growing. As long as it's reasonable, SBC is generally justified.
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An example of share dilution
One company notorious for share dilution is Snapchat parent Snap (SNAP -1.21%). Snap has used share-based compensation aggressively over the years but has also struggled to grow and turn a profit.
For example, since its 2017 initial public offering (IPO), Snap's shares outstanding has increased by about 60%. While SBC isn't the primary reason for the stock's challenges, its ongoing share dilution is a sign of poor management and the company's failure to create shareholder value.
Share dilution is complicated, and it's not always a negative for investors. If shares in a stock you own are being diluted, you'll want to understand why. It's also a good idea to assess whether it's hurting the value of the stock or is part of a long-term strategy to grow the business.