Build an SEC Filing Monitor

export SECAPI_API_KEY="your_api_key"

import { readFile, writeFile } from "node:fs/promises";

const statePath = new URL("./state.json", import.meta.url);
const apiKey = process.env.SECAPI_API_KEY;
if (!apiKey) throw new Error("SECAPI_API_KEY is required");

let state = { seen: [] };
try {
  state = JSON.parse(await readFile(statePath, "utf8"));
} catch (error) {
  if (error?.code !== "ENOENT") throw error;
}

const seen = new Set(state.seen ?? []);
const retainedAccessions = [];
const retained = new Set();
const reviewQueue = [];
for (const ticker of ["AAPL", "MSFT", "NVDA"]) {
  let cursor;
  do {
    const query = new URLSearchParams({ ticker, forms: "8-K,8-K/A", limit: "50" });
    if (cursor) query.set("cursor", cursor);
    const response = await fetch(`https://api.secapi.ai/v1/filings?${query}`, {
      headers: { "x-api-key": apiKey },
    });
    if (!response.ok) throw new Error(`${ticker}: ${response.status} ${await response.text()}`);
    const payload = await response.json();
    for (const filing of payload.data ?? []) {
      const accessionNumber = filing.accessionNumber;
      if (!accessionNumber) continue;
      if (!retained.has(accessionNumber)) {
        retainedAccessions.push(accessionNumber);
        retained.add(accessionNumber);
      }
      if (seen.has(accessionNumber)) continue;
      reviewQueue.push({
        ticker: filing.ticker,
        form: filing.form,
        filingDate: filing.filingDate,
        accessionNumber,
        filingUrl: filing.filingUrl ?? filing.provenance?.filingUrl ?? null,
        requestId: payload.requestId,
      });
      seen.add(accessionNumber);
    }
    cursor = payload.hasMore ? payload.nextCursor : null;
  } while (cursor);
}

for (const accessionNumber of state.seen ?? []) {
  if (retainedAccessions.length >= 5000) break;
  if (!retained.has(accessionNumber)) {
    retainedAccessions.push(accessionNumber);
    retained.add(accessionNumber);
  }
}

await writeFile(statePath, JSON.stringify({ seen: retainedAccessions }, null, 2));
console.log(JSON.stringify({ newFilings: reviewQueue.length, reviewQueue }, null, 2));

node monitor-filings.mjs