What it means
When a business starts, the founders own 100 percent of the company, split among a specific number of shares. As the business grows, it often needs to raise money from investors, grant shares to key employees, or buy other companies.
To do this, the business creates and issues new shares. Because the total number of shares increases, each existing share represents a smaller fraction of the overall business.
This matters deeply to managers and business owners because it affects both control and value. If your ownership percentage drops, your voice in major decisions weakens.
More importantly, future profits and dividends are split among a larger group, meaning your individual share of the financial rewards decreases unless the overall value of the company grows faster than the rate of dilution. In practice, dilution is a normal tool for growth.
Startups rarely have enough cash to hire top talent or build products without trading equity. Managers must balance the benefit of bringing in money or talent against the cost of giving away ownership.
The goal is to make the pie so much bigger that a smaller slice is still worth far more than your original bigger slice. To manage dilution, companies often use vesting schedules for staff and options that can only be exercised under certain conditions.
Keeping a close eye on your cap table, which is the master list of who owns what, ensures you always know how new share issues will impact current owners.
In practice
Real-world examples.
Example
TechStart founders own 100 shares, representing 100 percent. They issue 20 new shares to hire a chief technology officer. The founders now own 83.3 percent, experiencing a 16.7 percent dilution.
Example
GreenCafes issues new shares to raise 50,000 pounds for a second location. Because the total share count grows from 1,000 to 1,250, the original owner sees their stake drop from 100 percent to 80 percent.
Example
A manufacturing firm with five million shares issues one million more to fund a factory upgrade. Existing shareholders see their voting power and dividend share reduce by approximately 16.7 percent.
Think of it
“Imagine sharing a whole chocolate cake with one friend, giving you half each. If three more friends join the table, the cake must now be cut into five pieces. You still have a piece, but it is much smaller than before.
Formula
Calculation
Dilution Percentage = (New Shares Issued / Total Shares After Issuance) x 100. For example, if a company has 80 shares and issues 20 new ones, the total becomes 100. The calculation is (20 / 100) x 100 = 20 percent dilution.Case study
Seen in the real world.
BrightBooks, a fictional cloud accounting software provider, started with 1,000 shares held equally by two founders, Anna and Ben. To fund expansion, they raised 100,000 pounds from an angel investor in exchange for 250 newly created shares. After the deal, the total share count rose to 1,250. Anna and Ben each went from owning 50 percent of BrightBooks to owning 40 percent. Although their percentage ownership dropped, the cash injection allowed the business to hire sales staff and double its annual revenue within twelve months. The valuation of BrightBooks grew from 400,000 pounds to 2 million pounds. Consequently, Anna and Ben each held a 40 percent stake worth 800,000 pounds, a significant increase in personal wealth despite the dilution.
Watch out
Common mistakes.
- Assuming that issuing more shares always decreases your personal wealth.
- Forgetting to include employee stock options in future ownership calculations.
- Failing to track the cap table accurately as the business grows.
Questions
People also ask.
Is share dilution always a bad thing?
No. Dilution is often necessary to fund growth, hire great staff, or acquire other businesses. A smaller slice of a much larger pie is often worth more.
Can existing shareholders stop dilution?
Sometimes investors have anti-dilution rights, but for standard shareholders, dilution is a normal part of a company raising capital or expanding its team.
Does dilution affect the share price immediately?
When new shares are issued, the value of existing shares can drop initially, but if the new capital is used well, the overall company value increases over time.
From the founder's library
Take it further with the book.
Build your financial confidence beyond this definition. Shihan's full-length guide, Accounting Fundamentals, takes the same plain-English approach and turns it into a complete, practical playbook for non-finance managers, business owners and students - with chapter-end quiz answers and presentation slides included.
25% off with code MMHQ25, applied at checkout. Priced in USD - checkout may show the equivalent in your local currency.
View the book and save 25%