Can you build your own Polymarket bot? How much do you really make?

What a Polymarket bot can do

Three main strategies: arbitrage between markets, market making (capturing bid-ask spreads), and signal trading based on external data (polls, news, social sentiment).

Technically: Polymarket offers an API. A Python bot can read order books, open positions, and track P&L in a few hundred lines.

Arbitrage: looks easy, is not

Example: 'Trump wins 2024' on Polymarket at $0.52, on Kalshi at $0.48. Long Polymarket, short Kalshi, guaranteed $0.04 profit per share. Right?

Not quite. Funding two accounts, different fees, withdrawal delays, and the risk that one of the markets resolves before the other can be closed. Net edge often shrinks to zero or negative.

Plus: arbitrage windows on big markets close within seconds. Against institutional bots you are slow.

Market making: only profitable on big markets

Quoting on the bid and ask, capturing spread on every fill. Works fine on markets with €100k+ daily volume. Works poorly on small markets where you wait 30 minutes for a fill while your quote bleeds against news flow.

Realistic: a market making bot on the top 5 Polymarket markets can do 5-15% per month on deployed capital, if you manage inventory risk well. Not nothing, but not the 1000% per year influencers promise.

Signal trading: real edge here, but...

Examples: a new poll publishes, your bot fetches it within 2 seconds and recalculates the Polymarket price. Or: a politician tweets something relevant and your NLP pipeline triggers a trade before the market notices.

Problem: you compete against hedge funds with the same data, faster infrastructure, and better models. The edge is real but narrow and shrinks every month.

Honest expectation

A good self-built Polymarket bot, after 6 months of tweaking: 8-20% per month on deployed capital in a good month, -10% in a bad one. Not the screaming numbers from Twitter.

Time investment: 200+ hours to build, 2 hours per day to maintain. Comparable to a part-time job, not passive income.