PlatformAboutPricing

Product updates

What’s new at Theory A

Better ways to understand a business, test an idea, and keep track of what you own.

Here’s what changed and why it matters, with a few notes on the engineering behind it.

Selected milestones from the project history. Dates group related work; they aren’t exact launch dates. Earlier entries describe the product at the time.

2026

Performance

Keep researching. Your charts can reuse what you’ve already loaded.

Open a company in Analyze, then look at it in your portfolio or a comparison. Those views now share the same saved market data. Previously loaded charts can stay visible while fresh data arrives, including when a request fails.

Behind the update

  • One cache keys data by dataset, ticker, and fiscal period. It deduplicates in-flight requests, batches overlapping quote requests, and bounds history-fetch concurrency.
  • IndexedDB preserves public datasets across reloads, with expiry, eviction, and a memory fallback. Refreshes notify every subscribed view; private account data stays out of this cache.
Explore a company
Research

Read the argument. Try the assumptions.

A valuation article is more useful when you can question its numbers. New company studies and investing guides put charts beside the argument, with clearer explanations of what a business would need to earn. Explore the chart, change the view, and see where your own assumptions differ.

Behind the update

  • Articles reuse the application’s chart components and add editorial annotations, keeping research and product behavior connected.
  • Shared earnings-valuation calculations distinguish reported EPS from estimates and make the use of today’s share count explicit. Regression tests cover scaling and annotation placement.
Read the research
Alerts

Decide what price deserves another look.

You may like a business without liking its price. The portfolio’s old watchlist has become a dedicated Price Alerts view, where you can set upper and lower thresholds, compare them with price history, and adjust them in place. It’s easier to see which companies are getting close to the prices you care about.

Behind the update

  • US and China portfolios share the alert workflow, with saved alert changes reflected in the analysis and portfolio views.
  • Chart interactions and regression coverage handle threshold editing and historical date ranges. The retired predictions pages redirect to Portfolio, preserving older links.
Open Portfolio
Access & billing

Explore the core research tools for free.

Core stock and options research is now free, with clearly labeled advertising. The plans page separates lifetime ad-free access from Premium’s weekday alert emails and contract quote auto-refresh. AI is not included in either plan. New purchases remain paused while checkout verification is completed.

Behind the update

  • Billing reconciles current provider state instead of trusting webhook arrival order. Database leases, idempotency, and atomic entitlement updates handle retries and concurrent events.
  • Lifetime ownership and subscriptions are independent, so cancelling one does not erase the other. Tests exercise SQL rollback and test/live isolation; ad scripts run in an isolated iframe after opt-in.
See what each plan includes
Email

See what needs your attention before opening every chart.

The portfolio digest brings upcoming earnings, notable moves in your holdings, and open options into one email. Recent updates put the earnings calendar near the top and make the snapshot easier to scan on a phone. Weekday email delivery is a Premium feature.

Behind the update

  • Digest dates follow the US market date. An unavailable earnings calendar does not prevent the rest of the email from being assembled.
  • Option profit and loss respects whether a position was bought or sold. Compact HTML and plain-text versions keep the essential information readable across email clients.
Review email settings
Options

See what has to happen for an option to pay off.

A premium alone doesn’t tell you much. Open a contract to see its breakeven and profit or loss at different stock prices at expiration. The option chart also makes it easier to focus on nearby strikes and expirations, then connect a contract back to positions in your journal.

Behind the update

  • Payoff calculations account for call/put direction, premium, and contract size. Tests cover boundary cases separately from the chart rendering.
  • Implied-volatility estimates remain distinct from expiration payoffs, and unavailable probability inputs stay unavailable. Shared focus-window logic coordinates the chart’s detail view.
Explore an option chain
Learning

Winning more often can still leave you with less.

The Kelly Game lets you feel the difference between having an edge and betting too much. Replay the same coin flips at different bet sizes, then use the new explainer to see how repeated wins and losses compound. The size of the bet changes the outcome even when the flips stay the same.

Behind the update

  • Replays reuse the same outcomes across stake sizes, making the comparison about sizing rather than a luckier random run.
  • The game and explainer share log-growth calculations. Seeded sample paths and rounded SVG coordinates keep server and browser rendering consistent.
Play the Kelly Game
Charts

Keep the context. Choose which details to show.

Positions and forecasts now fit into the analysis chart as layers you can turn on when you need them. US and China analysis also share more of the same controls, so switching markets takes less relearning. Your date window stays part of the research workflow.

Behind the update

  • A shared chart-data pipeline and date-window model replace separate US and China implementations, reducing places where fixes can diverge.
  • Market-specific tests cover estimate normalization and chart ranges. Separate layers keep position and forecast overlays from duplicating the underlying chart.
Explore the chart layers
Valuation

Put your own expectations on the chart.

What if earnings grow more slowly? What if investors pay a lower multiple? Edit forecast earnings, compare low, average, and high estimates, or draw a growth path on the chart. You can see how an assumption changes the scenario without treating that scenario as a promised stock price.

Behind the update

  • Annual and quarterly earnings use explicit scaling, with a regression test for the double-multiplier error that could distort quarterly valuations.
  • The drawing tool translates chart coordinates into an annualized growth rate. Valuation controls expose different averaging methods instead of hiding that choice in one default.
Try a valuation scenario
Research

Two lines moving together are the start of a question.

The correlations workspace helps you investigate a relationship instead of stopping at a single score. Compare returns or price levels, change the time window, inspect the observations, and save a research snapshot. You can also check whether a relationship holds up in a separate period.

Behind the update

  • Series align on shared dates before returns are calculated, avoiding comparisons between one-day and multi-day moves. Missing observations remain explicit in lag analysis.
  • Pearson and Spearman methods, minimum sample requirements, and holdout periods make statistical choices inspectable. Saved research snapshots retain their data and analysis settings.
Investigate a relationship
Markets

Look beyond the stock you’re researching.

The Macro view brings market groups and ratio charts into one place. Compare how two assets have moved relative to each other, then look inside a market group at its constituents. It gives a company’s price move some wider context.

Behind the update

  • Ratio histories align observations by date and guard against invalid denominators, rather than dividing unrelated rows from two feeds.
  • Shared history-window utilities keep chart ranges consistent, with tests for missing observations and ratio calculations.
Explore the wider market
Portfolio

Judge the investment you actually made.

Buying a stock twice creates two different starting points. Portfolio now keeps those purchases as separate lots, with notes, cost basis, and closed-position history. Benchmark comparisons account for when and how much you invested, so you can ask what those same dollars would have done in the benchmark.

Behind the update

  • Benchmark paths simulate purchases using each lot’s entry date and cost basis, rather than comparing every holding with one arbitrary start date.
  • Stock lots and option positions feed a common portfolio view. Missing quotes no longer appear as a misleading 100% loss while data loads.
Review your positions
Mobile

Check a position without finding your laptop.

Portfolio and Analyze gained layouts built for a phone, including compact position details, touch-friendly chart controls, and pull to refresh. You can also add supported pages to your home screen for a more direct way back to your research.

Behind the update

  • Mobile views reuse portfolio and chart data while adapting the interaction model to smaller screens.
  • Page-specific web app manifests support standalone entry points. Refresh actions update data without requiring a full page reload.
Open your portfolio
Market coverage

Bring the same research questions to Chinese stocks.

China research added company search, financial charts, and portfolio tracking for supported Shanghai, Shenzhen, and Hong Kong listings. Chinese company names and local market context make it easier to find the business you mean and follow it from research to a position.

Behind the update

  • Exchange-aware symbol handling and bilingual company names connect search results to the right listing.
  • China portfolios reuse common portfolio components, while market-specific price formatting and data adapters handle differences in the source data.
Explore China research

2025

Options journal

Give each trade a history you can learn from.

The trading journal, now called Options Journal, brought entries, exits, open positions, and realized results into one place. See the contract’s timeline alongside earnings dates and review a closed trade with the details still attached. It’s easier to revisit a decision when you don’t have to reconstruct it first.

Behind the update

  • Profit-and-loss calculations distinguish bought and sold options, contract counts, and entry and exit prices.
  • Closing a trade requires an exit date when an exit price is supplied, keeping performance calculations tied to an actual holding period.
Open Options Journal

2024

Options

Put the business and the option on the same timeline.

Options research joined the platform with a view across strikes and expirations. Company earnings and estimates sit alongside option breakevens, so you can compare your view of the business with the stock price a contract needs at expiration. Filters help narrow a crowded chain to contracts worth examining.

Behind the update

  • The visualization maps contracts by expiration and strike or breakeven, with earnings events and financial overlays sharing the time axis.
  • Filters expose liquidity and option sensitivities, including delta, gamma, vega, and implied volatility, instead of making premium the only comparison.
See fundamentals and options together

2023

Valuation

A price becomes more useful when you can compare it.

Analysis charts added company estimates, adjustable valuation multiples, and a logarithmic scale for viewing proportional changes. Side-by-side comparisons made it easier to examine businesses using the same questions, then share the selected companies through a link.

Behind the update

  • Historical fundamentals and forward estimates use a common chart, with an explicit multiple connecting the financial measure to the valuation scenario.
  • Comparison selections synchronize with URL parameters so another reader can reopen the same set of companies.
Compare companies

2022

Screener

Find a smaller set of companies worth your time.

The screener grew into a way to explore a whole market, narrow it with financial filters, and see how the selection changed. Preset screens offered starting points. Shareable links let you keep a useful screen or send someone the same research question.

Behind the update

  • Filter state is encoded in the URL, preserving the selection beyond a single browser session.
  • Distribution charts and filters update each other, showing how a selection changes the financial and sector mix of the remaining companies.
Build a screen

2021

The beginning

Make a table of numbers easier to see.

Theory A began with a simple question: where does this company sit beside the others? The first stock browser turned financial metrics into visual rankings, with sorting and filters to help you notice differences that are easy to miss in a spreadsheet.

Behind the update

  • Deciles divide the stock universe into ten ranked groups. Metric-specific direction handling distinguishes measures where lower values are preferable from those where higher values are preferable.
  • Company, cash-flow, and market data were combined into a common set of stock records for visual comparison.
Explore today’s screener

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