Startups need to focus on product market fit and user acquisition before building the perfect system because things are guaranteed to change. But what happens after a startup's found product market fit and accrued a mountain of tech debt along the way? In this session Catherine will discuss her teams work at Stash as they navigated their way through an intense growth period and how they tackled paying down tech debt that was impending hyper growth. How do you recognise the scaling risks in your systems? Trading off challenges between monoliths and microservices How reducing cognitive load improves the resilience of a system Frameworks for identifying types tech debt and strategies for approaching them

1. Catherine Cornell’s UXDX talk 06. 01. 2021.

2. I’ve been a product manager for about 7 years.
Currently a Director of Product at Stash, focusing
on Stash’s Consumer Investing business.
Catherine Cornell.

3. Tech Debt

4. Stash is the first subscription platform
empowering middle-class Americans to
invest and build wealth.

5. Middle class Americans
Who is our market?
● 170m population size
● 45k - 145k household income
○ Median Stasher income is $50k
● Stash’s +5M customers are diverse -
coming from all over the US, with
unique financial backgrounds and
situations
● First time investors

6. 02
Over the Invest product’s 4 years focus has been
given to expanding number of products offered
and iterating to find the right fit for new investors.
Stash November
2019.
● 250 investments
● Executed orders twice a day
● Adding a new investment took about 3
weeks and required coordination between 4
teams

7. Here’s what Stashers are thinking…
- iOS 2.9.9 user
The ability to purchase partial shares and the
small monthly fees are great. Unfortunately,
you only have the ability to purchase whatever
is listed on the App. They might want to figure
out how to broaden their investment options
before one or all of the major trading sites
jumps into the partial share niche and squeeze
them out of business.
“
- Android 1.19.16.6 user
Very smooth and convenient interface... very
simple, yet offers wide selection of options.
Only drawback... Doesn't offer full range
amount of companies to invest in
“
*This is not an endorsement or a statement of satisfaction by any individual. Research based on a survey conducted online within the United States by Stash using SurveyMonkey technology in March 2021.

8. Scale from 250 to over 3,000
investments.
The mission:

9. We identified
some blockers.
● 10 pages document of KNOWN blockers
○ Mobile layout was designed with three segment
controls each lists to scroll through, already too
difficult sift through
■ iOS wouldn’t even be able to pull down
3,000 investment names let alone
constantly updating pricing
○ Investment pricing wasn’t scalable, we were
updating a single table in our monolith every 5
minutes
○ Tool the brokerage operators traders used to fill
orders tapped out at 500 investment names
○ Current 2 windows structure would not be able
to keep us with the volume of orders
○ Infinite unknown blockers

10. How did we back
ourselves into 10
pages of mistakes?

11. Tech Debt

12. Tech debt is the implied cost of
additional work in the future
caused by choosing an easy
solution today.

13. Product
is the cosigner of
tech debt.

14. ● Round-ups
● OKR planning
● New feature exploration
● Test win
Identifying debt.
Identifying Tech Debt

15. ● Good Citizen Rule
● Small Bites
● Design It In
● Demolition
Approaches for tackling tech
debt.
Tech Debt approaches

16. Opportunistic refactoring while coding features,
time for this is included in story points.
Good Citizen Rule.
● Reducing verboseness
● Removing dead/unused code
● Adding more test coverage
INSERT IMAGE HERE
Tech Debt approaches

17. Small improvements baked into a sprint. Pointed
tickets on the smaller side.
Small bites.
● Query optimizations
● Bug fixing
● Creating tools that suck up developer’s time
INSERT IMAGE HERE
Tech Debt approaches

18. Designed changes to a larger foundation when
implementing new features.
Design it in.
● Breaking pricing into a microservice out of a
monolith
● Moving to shared components in iOS
● Introducing new technologies into your
stack
INSERT IMAGE HERE
Tech Debt approaches

19. Major changes to a larger foundation. Often span
multiple sprints.
Demolition.
● Updating to Rails 5
● Rewriting a service in a new language
● Moving to streaming event architecture
INSERT IMAGE HERE
Tech Debt approaches

20. ● Calculated the maximum number of investments that could be added.
● 250ish
● Added 200
○ took note of the largest pain points in the process
○ uncovered some of the unknown blockers
○ validated the hypothesis that if we added more investments then we would see an increase in
key metrics
Snowball Method.
Our debt repayment plan

22. Buys and Deposits on the Stash Platform
*This material has been distributed for informational and educational purposes only represents an assessment as of 05/13/2021

23. 02
Paying off our tech
debt paid off.
142%
Increase in AUM.
13%
Increase in Customer
Dividends
37%
Increase in
Purchases

24. And paid off in dividends...
Google searches for “stocks” in the United States

25. New Stash subscriber creation

26. ● There will always be tech debt
● Be proud of your tech debt
● Have a process and feedback loop between engineering <> product
Recap.
Tech Debt approaches

27. catherine.cornell@stash.com
Questions?

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