Substack · Strategy · Mid · 45 to 60 minutes

What Should Substack Fix in Its Growth Loop?

Substack is a platform where writers publish subscription newsletters and manage free and paid readers. Answer this product management case and get it graded line by line against a weighted rubric.

Strategy
Growth loops
Prioritization
Metrics
Hypothesis driven thinking

The situation

The leadership team at Substack asks you, a PM focused on growth, to recommend where the company should place its next major bet. The company believes its growth comes from a reinforcing loop: creators publish on Substack, readers subscribe and engage, and that activity makes the platform more attractive to future creators and readers. But the team is split on which part of the loop is currently holding growth back. One view is that Substack needs to attract more high quality creators. Another view is that reader discovery and subscription behavior are the bigger issues. A third view is that the overall value proposition for someone choosing where to build a publication needs to be stronger. You need to advise the team on which area to prioritize over the next two quarters. The tension is that each path could plausibly improve growth, but product and go to market capacity are limited, and choosing the wrong bottleneck could slow the whole loop instead of accelerating it.

What to produce

Write a 1 to 2 page strategy memo.

Your answer must

Map Substack's core growth loop in plain language and identify the single most likely near term constraint.
Evaluate at least three strategic focus areas, including creator supply, reader discovery and subscription, and overall platform value proposition, with clear trade offs.
Recommend one priority for the next two quarters and outline 2 to 3 strategic bets or hypotheses at the product area level.
Define 3 to 5 success metrics, including at least one leading indicator and one lagging outcome, and explain how they connect to the loop.
List the main risks, assumptions, and the first evidence you would seek to confirm or overturn your recommendation.

Constraints

Stay within Substack's existing core model of subscription newsletters.
Do not assume acquisitions, exclusive creator deals, or a large paid marketing budget.
Your recommendation must fit a two quarter horizon and limited cross functional capacity.

Format

Use sections for loop diagnosis, options, recommendation, metrics, and risks.

How Substack actually played it

Argues Substack's loop depends on attracting good creators, who bring audiences and, in turn, attract more creators, and that its pitch addresses creator motives of ownership and monetization. Clear example of finding the constraint in a loop.

Find the one constraint that drives a loop
Address creators' motivations directly

Built from Substack's Core Growth Loop by Brian Balfour.