# Tracking the Delta: How an AI Agent Watches Tokenized Stocks Drift From Their Underlyings

> Source: <https://agentbadge.xyz/blog/bstock-delta-tracker-case>
> Published: 2026-09-23 00:00:00+00:00

# Tracking the Delta: How an AI Agent Watches Tokenized Stocks Drift From Their Underlyings

Tokenized stocks trade 24/7 while their underlyings sleep. We built a real-time delta tracker and exposed it to AI agents over MCP — with a 402 paywall on Arc.

A delta tracker computes the price divergence between a tokenized stock and its underlying in real time and serves it to AI agents over MCP — free tier 1 req/min, then HTTP 402 with an x402 payment on Arc Testnet.

Picture this: Apple trades at $336.45 on Nasdaq. Tokenized Apple (AAPLB on Binance) trades at $336.44 at the same moment. A penny apart — noise. But on a Saturday night, with Nasdaq asleep, AAPLB can drift to −2%. That is not noise anymore. That is a signal.

**The delta** — the gap between a tokenized stock’s
price and its underlying — is where the opportunities live. Humans
cannot watch 20+ tokens around the clock. A machine can. So we built a
tracker that computes the delta in real time and handed it to AI
agents.

*Binance streams token prices around the clock; Finnhub/Alpaca
supply the equity prices. DeltaEngine computes the delta, the market
phase (O/C/P) and the stale flag (15s without updates). The MCP server
exposes it to the agent through five tools, and Telegram receives an
alert the moment a delta crosses the 0.5% threshold.*

## What the tracker computes

For every bStock the tracker keeps two prices:

- **bStockPrice** — the token’s price on Binance, where
tokenized stocks trade 24/7;
- **underlyingPrice** — the real stock’s price from
market data providers (Finnhub, with an Alpaca fallback).

Delta in percent:
`(tokenPrice − stockPrice) / stockPrice × 100`. Alongside it,
three flags a trader actually needs:

- **phase** — is the stock market open (`O` ),
closed (`C` ), or in pre-market (`P` );
- **stale** — the price feed went quiet for more than 15
seconds, so treat the number with care;
- **inAlert** — the delta crossed the**0.5%
threshold** (configurable).

A live response looks like this:

```
{"symbol":"AAPLB","underlying":"AAPL","multiplier":1.0006,
 "bStockPrice":336.44,"underlyingPrice":336.45,
 "deltaPct":-0.064,"phase":"O","stale":false,"inAlert":false}
```

## How an agent uses it

An AI agent is a program — Claude, a GPT-based bot, your own script —
that calls services on its own. Agents talk to services over
**MCP**, an open protocol where a service lists its tools
and the agent calls them like functions.

The tracker is an MCP server with these tools:

- `get_delta` — delta for one symbol;
- `list_deltas` — all symbols at once;
- `get_quote` — current quote;
- `get_events` — event history (threshold crossings, stale
feeds);
- `get_digest` — the day’s summary.

```
curl -X POST https://agentbadge.xyz/mcp/bstock/tools/get_delta 
  -H "Authorization: Bearer $TOKEN" 
  -d '{"symbol": "AAPLB"}'
```

There is also Telegram: `subscribe_telegram` registers the
agent’s operator, and the tracker pushes a message whenever a delta
crosses 0.5%. No polling needed — the signal finds you.

## Freemium: a snapshot for free, the stream for a fee

The first request each minute is free. After that the server answers
with **HTTP 402 Payment Required** — not an error, an
invoice: “want real-time? pay”. The x402 standard lets the agent pay
automatically: 5 USDC on the Arc network buys 30 days of access. No
signup, no card, one on-chain transaction — gas paid in USDC too, an Arc
specialty. The server verifies the transaction on-chain and opens the
door. The same payment cannot be replayed — replay protection is built
in.

## Why a trader should care

A −0.06% delta is noise. A −2% delta on a closed exchange means “the token was sold off and the equity has not woken up yet”. Whoever sees it first captures the convergence. A person cannot monitor every token every second — an agent can, and it pays for its own data feed without a human in the loop.

*Next: inside the 402 paywall — how freemium works when the
customer is a machine.*

**Links**

- Agent guide (endpoints, limits, examples): [agentbadge.xyz/bstock-guide](https://agentbadge.xyz/bstock-guide)
- All articles in the series: [agentbadge.xyz/blog](https://agentbadge.xyz/blog)
- MCP endpoint:
`https://agentbadge.xyz/mcp/bstock/tools/get_delta`