# AnswerPool Busiest Filers

> AnswerPool Busiest Filers is a paid API for AI agents from answerpool.io, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Ranks SEC EDGAR filers by filing volume over a configurable time window (up to 5 years), optionally filtered to a specific form type.

## Facts

- Endpoint: GET https://answerpool.io/v1/sec/filings/top
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/answerpool-busiest-filers-fbb2ae43
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ovbf8Jw4kVc12_hu4hRvr

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability answerpool-busiest-filers-fbb2ae43
```

Example prompt: Show me the top 25 companies that filed the most Form D notices on SEC EDGAR over the last 365 days.

## When to prefer this

Choose this endpoint when you need a volume-ranked leaderboard of EDGAR filers for competitive intelligence, market surveillance, or identifying serial filers of a specific form type. It is more efficient than fetching and aggregating individual filing lists yourself. Prefer it over sibling endpoints like AnswerPool Form Trend (which gives market-wide monthly volume, not per-company rankings) or the 8-K item list endpoints (which filter by event type rather than ranking by filer).

## Known failure modes

- days parameter exceeds 1830 (5-year max) — validation error
- limit exceeds 100 — validation error
- Rare form type string yields zero results — empty filers array returned
- Payment not processed (HTTP 402) — call blocked until $0.02 USDC payment is fulfilled
- Stale index if EDGAR data ingestion lags — as_of timestamp will reflect last refresh

## How this service works

AnswerPool turns SEC EDGAR, the Federal Register, USAspending, NIH, BLS and OpenAlex into structured JSON answers that AI agents and developers fetch in one call. 69 endpoints free, no account; derived analyses $0.02–$0.05 per call by card credits or USDC (x402). MCP server, full provenance.

## Output

Returns a ranked list of filers with their CIK, company name, and filing count, plus metadata including the query window dates, as-of timestamp, form filter applied, and a disclaimer that the data is derived from public EDGAR filings and is not investment advice.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "title": "TopFilersIn",
     "properties": {
      "days": {
       "type": "integer",
       "title": "Days",
       "default": 90,
       "maximum": 1830,
       "minimum": 1,
       "description": "Length in days of the lookback window ending today, 1 to 1830, clamped at the start of index coverage. Default 90."
      },
      "form": {
       "anyOf": [
        {
         "type": "string",
         "maxLength": 12
        },
        {
         "type": "null"
        }
       ],
       "title": "Form",
       "default": null,
       "description": "Single EDGAR form type, matched exactly and case-insensitively (e.g. 8-K). Omit to count every form."
      },
      "limit": {
       "type": "integer",
       "title": "Limit",
       "default": 25,
       "maximum": 100,
       "minimum": 1,
       "description": "Maximum filers to return, ranked by filing count in the window, highest first. Default 25."
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "form": "D",
  "as_of": "2026-08-31T16:30:00Z",
  "filers": [
   {
    "cik": "0002150620",
    "company": "Upfront Secondary II-C, L.P.",
    "filings": 3
   }
  ],
  "index_to": "2026-08-28",
  "index_from": "2021-07-01",
  "window_days": 90
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/answerpool-busiest-filers-fbb2ae43/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from answerpool.io](https://www.zero.xyz/host/answerpool.io/llms.txt)