Generating data

The two entry points for data generation are generateStock (one ticker) and generateMarket (many).

Single stocks

```js import { generateStock } from 'stock-market-gen';

const stock = generateStock({ symbol: 'NOVA', name: 'Nova Corp', sector: 'Tech', startPrice: 180, drift: 0.12, // +12% per year, on average volatility: 0.28, // 28% annualised bars: 120, interval: '1d', startDate: '2024-01-01', seed: 'nova-demo' }); ```

Every option is optional. Here's what each one does:

Option	What it controls
symbol	Ticker. If you skip it, a random 2-5 letter symbol is generated.
name	Company name. Optional, you supply it — the package never invents one.
sector	Sector label. Optional, same idea.
kind	'stock' (default) or 'crypto'. Picks default ranges for price, drift, volatility.
startPrice	First bar's open price. If skipped, picked from the kind profile.
drift	Annualised drift (mean return). 0.05 = +5% per year.
volatility	Annualised volatility. 0.3 = roughly ±30% swings per year.
bars	Number of bars. Defaults to 100.
interval	Bar size. See Intervals.
startDate	Timestamp of the first bar. Date object, ms epoch, or ISO string.
seed	Anything (string or number). Same seed → same output.

Stock vs crypto

The kind option picks between two preset profiles:

Profile	startPrice range	drift	volatility
stock	$50 – $500 (uniform)	-15% to +25%/yr	10% to 60%/yr
crypto	$0.01 – $50,000 (log-uniform)	-30% to +60%/yr	60% to 150%/yr

js const tech = generateStock({ kind: 'stock', symbol: 'TECH', bars: 365 }); const btc = generateStock({ kind: 'crypto', symbol: 'BTC', bars: 365 });

You can still override anything individually — kind only affects values you didn't set.

Markets

A market is just an array of stocks. Two ways to build one:

Auto-generated (random tickers)

```js import { generateMarket } from 'stock-market-gen';

const market = generateMarket({ count: 8, bars: 90, interval: '1d', seed: 'demo' }); ```

You get 8 stocks with random symbols and no name / sector. Same seed → same market every time.

Hand-picked companies

Pass a stocks array. Any field you set is honored, anything else falls back to the shared options.

js const market = generateMarket({ bars: 90, interval: '1w', startDate: '2024-01-01', seed: 'custom', stocks: [ { symbol: 'NOVA', name: 'Nova Corp', sector: 'Tech', startPrice: 250 }, { symbol: 'HRBR', name: 'Harbor Bank', sector: 'Finance', volatility: 0.18 }, { symbol: 'PEAK', name: 'Peak Energy', sector: 'Energy', drift: -0.05, volatility: 0.45 }, { symbol: 'GRVN' } // name and sector left empty ] });

Symbol uniqueness

generateMarket keeps symbols unique within the market. If you supply some explicit symbols and let others auto-generate, the auto-generated ones avoid collisions.

Reproducibility

Same seed, same output. Forever. On any version of Node.

js const a = generateStock({ bars: 50, seed: 'pinned' }); const b = generateStock({ bars: 50, seed: 'pinned' }); // a.bars deep-equals b.bars

When you call generateMarket with a seed, that seed deterministically picks per-stock seeds, so the whole market is reproducible too.

What you get back

Every stock looks like:

js { symbol: 'NOVA', name: 'Nova Corp', sector: 'Tech', kind: 'stock', startPrice: 180, interval: 86400000, // ms representation of '1d' bars: [ { time: 1704067200000, // unix epoch in ms date: '2024-01-01T00:00:00.000Z', // ISO 8601 open: 180.00, high: 182.34, low: 179.10, close: 181.27, volume: 1820411 }, // ... ] }

It's plain JSON-safe data. JSON.stringify(stock) round-trips cleanly — see Custom data for save/load patterns.

Next steps

• Intervals — every bar size, including calendar-aware months and years.
• Custom data — supply your own prices or full OHLC bars.
• Charts — render what you generated.