Sell in May
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User guide

Documentation

How Sell in May turns regime-aware pattern matching into probabilistic forecasts — and how to read every card in the app.

Overview

Sell in May is a professional market analysis application that helps you understand potential future price behavior of stocks by comparing current patterns to historically similar situations. Unlike simple charting apps, Sell in May is regime-aware — it recognizes that markets behave differently in different conditions and only shows you patterns from similar market environments.

Key features
  • Regime-aware pattern matching from 10 years of historical data
  • Optional AI-powered forecasting with probabilistic scenarios
  • Fundamentals analysis with DCF calculator
  • Peer correlation heatmap with configurable peer list
  • Risk & performance metrics (Sharpe, Sortino, VaR, beta)
  • On-device technical indicators (RSI, MACD, Bollinger Bands, ATR, OBV)
  • Macro-economic context with World Bank and IMF fallbacks
  • 100% on-device processing for complete privacy
  • Works offline after initial data download
  • Professional-grade technical analysis tools

Getting started

First launch

When you first open Sell in May, the app will:

  • Request permission to access the internet (needed to download current market data)
  • Begin downloading historical data for popular stocks and indexes
  • Set up local storage for caching market data

Note

The initial data download may take a few minutes. Once complete, the app works offline for previously analyzed stocks.

Selecting a stock

To analyze a stock:

  1. Tap the search or symbol entry field
  2. Enter a stock symbol (e.g., AAPL, MSFT, TSLA)
  3. The app will fetch current and historical data for that stock
  4. Analysis results will appear automatically

Selecting market context

You can also select one or more market indexes (like S&P 500, Nasdaq) to provide context for regime detection. The app uses these to understand the broader market environment.

Analyzing stocks

What the app does

When you select a stock, Sell in May:

  1. Detects the current market regime — classifies volatility, trend, and risk sentiment
  2. Finds similar historical patterns — searches 10 years of data for price curves that look similar under comparable market conditions
  3. Generates probabilistic forecasts — shows you what happened after those similar patterns, giving you a range of possible outcomes
  4. Provides confidence metrics — tells you how reliable the matches are

Understanding the analysis view

The main analysis screen shows:

  • Current Price Chart — recent price movement of the selected stock
  • Market Regime Badge — current market conditions (volatility, trend, sentiment)
  • Pattern Matches — historical patterns that are similar to the current situation
  • Forecast Scenarios — probabilistic outcomes showing possible future price movements
  • Confidence Metrics — how reliable the analysis is
  • Fundamentals Card — company key stats and DCF intrinsic value
  • Peer Correlation Card — correlation heatmap with peer symbols
  • Risk Metrics Card — risk/return metrics vs benchmark
  • Technical Indicators Card — RSI, MACD, Bollinger, ATR, OBV

Understanding results

Pattern matches

Pattern matches show you historical price curves that are similar to the current situation. Each match includes:

  • Similarity Score — how closely the historical pattern matches (higher is better)
  • Date Range — when this pattern occurred historically
  • Forward Outcome — what happened to the price after this pattern
  • Regime Match — whether the market regime was similar

Tip

Patterns with similar market regimes are more relevant. The app gives these patterns a similarity boost.

Probabilistic forecasts

Instead of giving you a single prediction, Sell in May shows you a range of possible outcomes:

  • Return Percentiles — 10th, 25th, median, 75th, and 90th percentile outcomes
  • Confidence Intervals — the range where most outcomes are likely to fall
  • Downside Risk — probability of significant losses
  • Expected Volatility — how much price movement to expect
Example: If the forecast shows:
• 25th percentile: -5% (25% chance of losing 5% or more)
• Median: +3% (50% chance of gaining 3% or more)
• 75th percentile: +8% (25% chance of gaining 8% or more)

This means there's a 50% chance of gains between -5% and +8%, with the most likely outcome around +3%.

Confidence metrics

The app provides several confidence indicators:

  • Match Quality — how similar the historical patterns are
  • Regime Consistency — how many matches come from similar market regimes
  • Sample Size — how many historical patterns were found

Important

Higher confidence doesn't guarantee accuracy. Markets are unpredictable, and past performance doesn't guarantee future results. Always use this as one tool among many in your investment research.

What's new in this update

Version 1.0.4 adds powerful new analysis tools to help you make better investment decisions:

Fundamentals Analysis

View key company statistics and estimate intrinsic value with an interactive DCF calculator.

Peer Correlation

Visualize how your stock correlates with peers like SPY, QQQ, and IWM on a heatmap.

Risk Metrics

Track return, volatility, Sharpe ratio, Sortino ratio, max drawdown, and VaR.

Technical Indicators

Monitor RSI, MACD, Bollinger Bands, ATR, and OBV—all computed on-device.

Fundamentals analysis

The Fundamentals card provides key company statistics and an interactive DCF (Discounted Cash Flow) calculator to estimate intrinsic value.

Key statistics

The app displays essential fundamentals for any company:

  • Market Cap — total market value of the company
  • P/E Ratio — price-to-earnings ratio
  • EPS — earnings per share
  • Dividends — annual dividend yield and payout
  • P/B Ratio — price-to-book ratio
  • P/S Ratio — price-to-sales ratio
  • 52-Week Range — high and low prices over the past year
  • Moving Averages — 50-day and 200-day moving averages

DCF calculator

The DCF calculator estimates intrinsic value using a two-stage model:

  • Projection Stage — projects free cash flow for 5 years using growth rate assumptions
  • Terminal Stage — uses the Gordon Growth Model for perpetual growth
  • Discount Rate — WACC (Weighted Average Cost of Capital) to discount future cash flows

Output

The DCF calculator outputs:

  • Enterprise Value — total company value
  • Equity Value — value available to shareholders
  • Intrinsic Value Per Share — fair value per share
  • Upside/Downside — difference between intrinsic value and current price

Tip

Adjust the growth rate, terminal growth rate, and discount rate to see how different assumptions affect intrinsic value.

External resources

Access external resources directly from the app:

  • Yahoo Finance News
  • Yahoo Finance Quote Page
  • SEC EDGAR Filings

Peer correlation

The Peer Correlation card shows how your selected stock's returns correlate with a configurable list of peer symbols. Understanding correlation helps you:

  • Diversify your portfolio by avoiding highly correlated holdings
  • Identify sector rotations
  • Understand how your stock moves relative to the broader market

Default peer list

The default peer list includes major market indexes and sector ETFs:

  • SPY — S&P 500
  • QQQ — Nasdaq 100
  • IWM — Russell 2000
  • XLK — Technology
  • XLF — Financials
  • XLE — Energy

Understanding correlation

Correlation values range from -1 to +1:

  • +1.0 — perfect positive correlation (move together)
  • 0.0 — no correlation (independent movement)
  • -1.0 — perfect negative correlation (move opposite)
Example: If your stock has a 0.85 correlation with QQQ, it means when QQQ goes up 1%, your stock tends to go up 0.85%. A correlation of -0.3 would mean your stock tends to move opposite to QQQ.

Heatmap visualization

The detail view shows a color-coded heatmap:

Green · High positive correlation Red · Negative correlation White/Gray · Near-zero correlation

Lookback period

Configure how far back to calculate correlations:

  • 30 days (1 month)
  • 60 days (2 months)
  • 90 days (3 months)
  • 180 days (6 months)
  • 252 days (1 year)

Risk & performance metrics

The Risk Metrics card provides comprehensive risk and performance analytics versus a configurable benchmark (default: SPY).

Return metrics

  • Annualised Return — expected yearly return based on the lookback period

Volatility metrics

  • Annualised Volatility — standard deviation of returns, annualised
  • Daily VaR (95%) — Value-at-Risk at 95% confidence (historical)
  • Daily VaR (99%) — Value-at-Risk at 99% confidence (historical)
  • Parametric VaR (95%) — Parametric VaR assuming normal distribution

Risk-adjusted metrics

  • Sharpe Ratio — return per unit of volatility (risk-free rate = 0)
  • Sortino Ratio — return per unit of downside volatility
  • Calmar Ratio — annualised return / max drawdown

Drawdown metrics

  • Max Drawdown — largest peak-to-trough decline

Beta

  • Beta — sensitivity relative to benchmark (OLS regression)

Benchmark

Compare your stock's risk/return profile against a benchmark like SPY, QQQ, or any other symbol. Beta measures how much your stock moves relative to the benchmark.

Understanding metrics

Sharpe Ratio: A Sharpe of 1.0 means you earned 1 unit of return per unit of risk. Generally, higher is better.

Sortino Ratio: Only penalizes downside volatility, so it's better for portfolios concerned with protecting capital.

Beta: Beta > 1 means more volatile than benchmark; Beta < 1 means less volatile.

VaR interpretation

Value-at-Risk answers: "What's the most I could lose?"

Example: 95% Daily VaR of 2% means there's a 5% chance you could lose more than 2% on any given day. 99% VaR of 3% means there's only a 1% chance of losing more than 3%.

Lookback period

Configure the lookback for calculations:

  • 90 days (half-quarter)
  • 180 days (quarter)
  • 252 days (1 year)
  • 504 days (2 years)

Technical indicators

The Technical Indicators card displays popular technical analysis metrics, all computed on-device from OHLCV (Open, High, Low, Close, Volume) data.

RSI (Relative Strength Index)

Measures the magnitude and speed of price changes. Scale: 0-100.

  • RSI > 70 — overbought (potential sell signal)
  • RSI < 30 — oversold (potential buy signal)

The app uses Wilder smoothing for RSI calculation.

MACD (Moving Average Convergence Divergence)

Trend-following momentum indicator showing the relationship between two moving averages.

  • MACD Line — 12-period EMA minus 26-period EMA
  • Signal Line — 9-period EMA of MACD
  • Histogram — MACD minus Signal

Bollinger Bands

Volatility bands placed above and below a moving average.

  • Upper Band — 20-period SMA + 2 standard deviations
  • Middle Band — 20-period SMA
  • Lower Band — 20-period SMA - 2 standard deviations
Interpretation: Price near upper band may indicate overbought; price near lower band may indicate oversold. "Squeeze" (narrow bands) often precedes significant moves.

ATR (Average True Range)

Measures market volatility. Represents the average range over N periods.

  • Uses Wilder smoothing (similar to RSI)
  • 14-period default
Example: ATR of 2.5 means the stock typically moves $2.50 per day. Use ATR to set stop-loss distances (e.g., 2x ATR for stop).

OBV (On-Balance Volume)

Cumulative volume indicator that adds/subtracts volume based on price direction.

  • Volume added — when price closes higher
  • Volume subtracted — when price closes lower
  • Volume unchanged — when price closes flat
Interpretation: OBV rising with price rising = healthy uptrend. OBV falling with price rising = divergence (potential reversal).

Important

Technical indicators are not predictive signals. They describe past price behavior. Always use multiple indicators and fundamental analysis for investment decisions.

Market regime detection

Sell in May automatically classifies the current market environment across three dimensions:

Volatility

Low · VIX below 15 Medium · VIX 15-25 High · VIX above 25
  • Low — markets are calm, VIX typically below 15
  • Medium — normal market fluctuations, VIX 15-25
  • High — elevated uncertainty, VIX above 25

Trend

  • Trending — clear upward or downward price movement
  • Mean-Reverting — prices oscillating around a central value
  • Neutral — no clear trend pattern

Risk sentiment

  • Risk-On — investors are optimistic, buying riskier assets
  • Risk-Off — investors are cautious, seeking safety
  • Neutral — balanced sentiment

Why this matters

Markets behave very differently in high volatility, risk-off environments versus low volatility, risk-on environments. By matching patterns from similar regimes, the app provides more relevant historical comparisons.

Macro-economic context (optional)

Sell in May can integrate Federal Reserve economic data to provide deeper context about the broader economy. This feature is optional and requires a free FRED API key.

What is FRED?

FRED (Federal Reserve Economic Data) is a database maintained by the Federal Reserve Bank of St. Louis containing thousands of economic indicators. When enabled, Sell in May uses this data to:

  • Classify the macro-economic regime (Expansion, Slowdown, Recession, Recovery, Stagflation)
  • Calculate recession probability
  • Boost similarity scores for patterns from similar economic conditions

Setting up FRED integration

  1. Get a free API key from fred.stlouisfed.org
  2. Open Sell in May Settings
  3. Enter your FRED API key
  4. The app will begin downloading economic indicators

Note

The app works perfectly without a FRED API key. You'll still get regime detection based on market volatility (VIX), but without the additional macro-economic context.

World Bank & IMF fallbacks

When FRED data is unavailable for certain indicators (CPI, unemployment), the app automatically falls back to alternate sources:

  • World Bank — global development data
  • IMF — International Monetary Fund data

The fallback priority is: FRED → World Bank → IMF

Tip

You can enable or disable World Bank and IMF fallbacks independently in Settings. This ensures you get macro data even when FRED returns no data for a requested date.

Economic indicators used

When FRED is enabled, the app tracks:

  • Interest rates (Federal Funds Rate, Treasury yields)
  • Yield curve spread (10-year minus 2-year Treasury)
  • Credit spreads (High yield, TED spread)
  • Inflation metrics (CPI, breakeven rates)
  • Economic growth (Unemployment, consumer sentiment)

Note: World Bank and IMF provide CPI and unemployment only. Other high-frequency indicators (Treasury yields, yield curve, breakeven, TED, HY credit, fed funds, sentiment) only come from FRED.

Macro regimes

The app classifies the economy into five regimes:

  • Expansion — healthy economic growth
  • Slowdown — growth decelerating
  • Recession — economic contraction
  • Recovery — improving from recession
  • Stagflation — high inflation with slow growth (rare)

Settings & configuration

Analysis parameters

Sell in May offers 20+ configurable parameters to customize your analysis:

  • Pattern Lookback Period — how far back to search for patterns
  • Similarity Threshold — minimum similarity score for matches
  • Number of Matches — how many historical patterns to show
  • Forecast Horizons — time periods for predictions (5, 10, 20 days)
  • Regime Sensitivity — how strictly to filter by market regime

Peer correlation

  • Peer Symbols — comma-separated list of peer symbols (default: SPY, QQQ, IWM, XLK, XLF, XLE)
  • Peer Correlation Lookback — days to calculate correlations (30/60/90/180/252)

Risk metrics

  • Risk Benchmark — benchmark symbol for beta and comparison (default: SPY)
  • Risk Lookback — days to calculate risk metrics (90/180/252/504)

Macro data (optional)

  • FRED API Key — free API key from fred.stlouisfed.org
  • Use World Bank as fallback — enable/disable World Bank fallback for CPI/unemployment
  • Use IMF as fallback — enable/disable IMF fallback for CPI/unemployment

Data refresh

You can manually refresh market data or configure automatic background updates. The app caches data locally, so you can analyze stocks offline after the initial download.

Display options

  • Dark mode toggle
  • Chart style preferences
  • Confidence metric display options

Privacy & data

Complete privacy

All analysis runs on your device. Your data never leaves your iPhone. No cloud backend, no user accounts, no data collection, no tracking or analytics, and no sharing with third parties.

What data is stored?

The app only stores:

  • Market data — stock prices and economic indicators (cached locally)
  • Your settings — analysis parameters and preferences (stored on device)

The app does not store:

  • Your stock selections or watchlists
  • Your analysis history
  • Any personal information
  • Any usage data

Internet usage

The app only uses the internet to:

  • Download current market data from Yahoo Finance, FRED, or Stooq
  • Update historical price data

Once data is downloaded, the app works completely offline for previously analyzed stocks.

Data sources

Market data comes from free, public APIs:

  • Yahoo Finance — primary source for stock prices
  • FRED — economic indicators (optional, requires API key)
  • World Bank — fallback for CPI and unemployment
  • IMF — secondary fallback for CPI and unemployment
  • Stooq — fallback for extended historical data

For more detail, read the full Privacy Policy.