BCG growth-share matrix: what it is and what to do instead

The idea worth keeping

Not as boxes to fill, but as questions that fall out of the maths of the goal:

• How much would each investment add to profit each year, and what does it cost?
• Is the market growing, and does a bigger share actually bring lower cost or higher price here?
• Which units need cash, and which generate it?

Why reaching for it fails in an interview

• It is generic. Stars, cash cows, question marks and dogs can label any portfolio without a single profit number.
• It misses the driver that matters. It ranks by growth and share, but the decision turns on the return each investment earns, which the matrix leaves out.
• It sounds rehearsed. "Milk the cash cow, invest in the star" sounds learned and can point the wrong way.

What to do instead: a worked case

1. 1

   Pin the question

   Pick the two brands where 20 million adds the most profit each year, and check the risk.

2. 2

   Write the maths of the goal

   • Return on investment = extra profit per year / 20 million
   • Extra profit = extra sales x profit margin of that category
3. 3

   Use what you know about the business

   • In consumer goods, growth comes from shelf space, distribution and new product lines; margins differ a lot by category.
   • A brand with a big share in a slow market can still earn a high return on a well-chosen premium line.
   • Small brands in hot categories often need heavy, low-margin promotion to win shelf space.

   The structure that falls out of it

   • Extra profit from each brand
     • Extra sales the plan would bring
     • Margin in that category
   • Cost and timing
     • 20 million each
     • Years to pay back
   • Risk
     • How certain the extra sales are

   Hypothesis: The matrix would back the energy drink (a question mark), but its low margin may make it a poor use of money; I would rank by return.

4. 4

   Find the facts that decide it

   • Snacks (growing 8%, the star): extra profit 5 million a year, a 25% return.
   • Soap (growing 1%, the cash cow): a premium range would add 2.8 million a year, a 14% return.
   • Energy drink (growing 12%, the question mark): 1.6 million a year after heavy promotion, an 8% return. Cereal (shrinking 2%, the dog): 1 million a year, a 5% return.
5. 5

   Say so what

   Invest in snacks (25% return) and the soap premium range (14%), not the energy drink (8%), even though the matrix says to milk soap and back the energy drink. Keep cereal for cash and review whether to sell it. The risk is missing a fast-growing category, so revisit the energy drink if its margin improves.

Build the acumen behind it

The worked case used two things a list cannot give you: the five moves, and knowing how this kind of business makes money. These pages teach both.