Challenges/Golden Analytics/Full Stack Engineer/Household Portfolio Rebalancer

Household Portfolio Rebalancer

Description Someone manages their household's investments across multiple broker accounts and wants to keep their portfolio aligned to a chosen asset-allocation target — and to be able to change that target over time. Their broker only…

Full Stack
Fintech
Data Modeling
Agentic Development
Estimated Time:
2 hours
Difficulty:Intermediate
Status:Not started
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What You'll Be Doing

Description

Someone manages their household's investments across multiple broker accounts and wants to keep their portfolio aligned to a chosen asset-allocation target — and to be able to change that target over time. Their broker only gives them a flat CSV export of raw positions (symbol-level holdings), not a view organized the way they actually think about their money: File to be found here.

Your job is to close four gaps:

  1. The data isn't in a usable shape. The provided CSV is a flat, symbol-level export across multiple accounts. Turn it into something organized the way the user actually thinks about their money.
  2. There's no concept of a target. The user thinks in terms of asset classes (US Equity, International, Gold, Cash, Treasuries, etc.) and target percentages, but the brokerage only shows individual ticker holdings. You'll need to design how tickers map to asset classes — the sample data does not come with this mapping; that design is part of the challenge.
  3. Rebalancing math is tedious and error-prone by hand. Given a current allocation and a target allocation, figure out exactly which symbols to buy and sell — and how much — to reach the target. Cash cannot move between accounts, so each account must be rebalanced independently, funded and absorbed only by its own money-market/cash position.
  4. Some accounts are more liquid than others. The user may prefer to hold more cash in certain accounts (e.g., maximize cash in a brokerage account rather than a retirement account) because that account is more accessible. Your solution should account for this preference.

Build a working tool — not a script or notebook — where a user can see their current allocation, edit a target allocation, and get back the exact set of transactions needed to reach it.

Constraints to Consider

  • No paid or proprietary services required. Your solution must run locally from documented setup steps — no infrastructure budget assumed.
  • The CSV export format is fixed. You cannot change what the brokerage sends. Your solution must ingest the provided format as-is.
  • Cash cannot move between accounts. Each account rebalances independently, funded only by its own money-market/cash position — never assume you can use one account's cash to fund a trade in another.
  • 120-minute total budget, including your video. Prioritize a complete, working core experience over a partially-built comprehensive one.

AI Usage Guidance

We expect you to use AI tools while building this. We evaluate how you use them — not whether you used them. Evidence of iteration, redirection, and critical evaluation scores higher than a polished output with no process documentation. Note: this challenge does not require your solution to call an AI API at runtime — the AI evaluation is entirely about your build process.

The single highest-signal indicator: your video answer to the mandatory AI question. If you cannot name a specific moment where you redirected AI output, evaluators will assume you did not.

Mandatory AI question for your video: Walk me through one moment where you disagreed with, pushed back on, or redirected what the AI gave you — and what you did instead. Name the specific moment. Explain what the AI produced that didn't meet the bar, what you did differently, and why.

Speak naturally. Communication is assessed on clarity of technical ideas and logical structure — not verbal polish, accent, or filler words.

Submission: Upload each deliverable as a separate file directly on the Provn platform: your primary artifact, your README document (Sections A, B, and C), and your video walkthrough (MP4 or MOV).

What You'll Accomplish

Demonstrate ability to transform raw, unstructured financial data into a coherent, usable domain model

Build a full-stack tool that turns an ambiguous financial requirement into a usable interface

Design and implement a constrained rebalancing algorithm that respects real-world limitations (per-account cash isolation, liquidity preference)

Communicate architectural decisions and trade-offs clearly to a technical audience

Demonstrate effective, critical collaboration with AI tools throughout the build process

How Your Work Will Be Scored

Data Modeling & Rebalancing Logic (30%): A strong submission correctly computes per-account rebalancing trades that respect cash isolation, and implements the liquidity preference in a way that generalizes beyond the single example described.Full-Stack Execution & Product Craft (25%): A strong submission is a working, usable end-to-end tool — not a script — that makes a dense financial dataset easy to understand and trust.Technical Communication & Decision-Making (15%): A strong submission clearly explains specific architectural decisions and trade-offs, in both the README and the video.AI Fluency (20%): A strong submission shows iterative, critical collaboration with AI — catching and correcting AI mistakes, not accepting first-pass output.Resume & Background (10%): Assessed from your submitted resume, not your challenge artifacts — evaluated separately for directly relevant full-stack and AI-building experience.

What to Submit

File 1 — Working Application:

Any FileRequired

Format: no restrictions

A full-stack tool where a user can: view their current holdings reorganized by asset class, define/edit a target allocation across asset classes, and see the exact buy/sell transactions needed per account to reach that target — respecting the cash-isolation and liquidity-preference considerations above. Any tech stack is fine.

Please use the CSV file found at this link.

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File 2 — README Document:

DocumentRequired

Format: .pdf, .doc, .docx, .rtf, .txt, .md

Three required sections —

Section A: Written analysis (300–500 words). Your approach to reshaping the raw data, how you modeled the asset-class target, and your rebalancing algorithm's design and trade-offs.

Section B: Architectural decisions + edge case reasoning. Explain your key architectural decisions (how you structured the data model, the rebalancing logic, and the liquidity-preference approach, and why). Then, without AI assistance, explain in your own words how your solution handles each of the following three edge cases:

  1. An account's required buys exceed what that account's own cash/money-market position can fund (remember: cash can't move between accounts).
  2. A single position is over-weighted for the account it's held in, but rebalancing it there would leave that specific account off its own target — while a different account already meets its target for that asset class.
  3. A computed trade implies buying a fractional share of a security that doesn't support fractional trading.

Section C — AI Usage Log (Mandatory): This is not a trick. We want to see how you work with AI — not whether you used it. In a short section of your README, document your AI collaboration process. For each significant interaction with an AI tool, briefly note: what you asked the AI to help with / what it gave you / what you kept, changed, or rejected — and why. Three interactions documented is sufficient. The log does not need to be exhaustive.

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File 3 — Video Walkthrough (5–7 minutes):

VideoRequired

Format: .mp4, .mov, .webm

Record as MP4 or MOV and upload directly on the Provn platform as a separate file. Cover: (1) summary of the problem and your solution, (2) a live demo of your application, (3) your Section B architectural decisions, (4) the mandatory AI question (see AI Usage Guidance above), (5) what you'd do differently with more time. A code walkthrough is not necessary. Speak naturally — we assess clarity of technical ideas and logical structure, not verbal polish, accent, or filler words.

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