Silver Edge: How Options-Implied Probability Reveals Mispricings on Kalshi's Weekly Silver Market

Two markets. Same underlying. Different prices.

Kalshi's KXSILVERW weekly contract settles every Friday at 5pm Eastern on Pyth Network's XAG/USD feed. SLV — iShares Silver Trust — options trade on the same physical silver, settled through a different mechanism. When the options chain prices a 76% probability that silver closes above $70.99 on Friday, and Kalshi's book is pricing that same outcome at 88%, one of those two prices is wrong.

The Silver Edge tool measures the gap, daily, every strike on the weekly board. This is how it works, why it works, and what today's snapshot looks like.

The Thesis

A binary contract on Kalshi pays $1 if a condition resolves YES, $0 otherwise. The contract price is a probability statement: 88¢ on a "silver above $70.99" YES contract means the market is collectively saying there's an 88% chance.

An equivalent statement is hidden inside any liquid options chain on the same underlying. Black-Scholes — the same equation that prices SLV calls and puts on Robinhood — contains a probability term: N(d2), the risk-neutral probability that the underlying ends above the strike. That number is exactly what a Kalshi YES contract is supposed to represent.

When those two numbers disagree by more than the round-trip trading cost, you have an edge.

Why Pyth XAG/USD Matters

Settlement source determines truth. Kalshi publishes the settlement source for every series in its settlement_sources metadata. For KXSILVERW it's Pyth Network's XAG/USD price feed at exactly 5:00 PM Eastern on Friday. We pull the same Pyth feed (Hermes API) for our spot reference, so the number on our tool page is the actual number Kalshi will use to settle.

That alignment matters more than it sounds. Most "silver price" feeds you see online — Yahoo Finance, Kitco's frontend, broker quote screens — pull from different aggregators with their own latency, different last-trade definitions, and different cutoff times. If your model uses a feed that's even one tick away from Pyth's reference, you're modeling a slightly different question than the one Kalshi is settling.

Why SLV Options Are the Right Comparison

SLV is a physically-backed silver ETF. The fund holds silver bullion in trust; share price tracks spot silver with a small management-fee drag and sub-1% tracking error over short horizons. The options chain on SLV has deep weekly liquidity — bid-ask spreads on at-the-money strikes routinely under five cents.

Two reasons this beats other options sources:

1. Same underlying. A Kalshi market on silver-spot and an SLV option are both positions on the same metal price. The translation is one multiplication: K_slv = K_silver × (SLV_price / silver_spot). Today's ratio is $64.84 / $73.51 = 0.882.

2. Honest IV. Yahoo Finance publishes an impliedVolatility field on options data. It's broken — quantized in powers of 2 (0.5, 0.25, 0.125) for thinly-traded strikes. We don't trust it. We back-solve IV ourselves from the option's last traded price using Brent's method on the Black-Scholes formula, then build a smile across the chain. Numbers we publish are computed, not scraped.

The Math, Step by Step

For each Kalshi strike K on the upcoming weekly event:

1. Translate K from silver-$ to SLV-$ space:
   K_slv = K * (SLV_price / silver_spot)

2. Look up implied volatility at K_slv from the SLV smile.

3. Apply Black-Scholes to silver-spot directly:
   d1 = [ln(S/K) + (r - q + σ²/2)·T] / (σ·√T)
   d2 = d1 - σ·√T
   P(S_T > K) = N(d2)

4. Pull Kalshi's executable YES price:
   - tight book (≤10¢ spread): use mid
   - wide or one-sided book: use mid if both sides exist, else last
   - never trust a stale last_price over a live two-sided quote

5. Edge in percentage points:
   edge_pp = options_prob - kalshi_yes_implied

A positive edge means the options market thinks silver is more likely above K than Kalshi prices. BUY YES. A negative edge means options think it's less likely. BUY NO.

The 5pp threshold is intentional. Kalshi charges a quadratic fee on contract size, the SLV options chain has its own bid-ask drag, and you'll cross the Kalshi spread on entry and exit. Five percentage points is roughly twice the round-trip friction on a moderately-sized trade — anything below that gets flagged PASS.

The April 30, 2026 Worked Example

Here's the live snapshot at 12:41 UTC on April 30:

• Pyth XAG/USD spot: $73.51
• SLV last: $64.84
• ATM SLV IV: 60% annualized
• Event: KXSILVERW-26MAY0117, closes Friday May 1 at 5:00 PM ET
• Time to settle: 1.3 days

The full weekly board has 40 strikes from $55.99 up to $94.99. Eight of them clear the 5pp edge threshold. Here are the top calls:

The top call is BUY NO $70.99. The book has a tight two-sided market: bid 80¢ / ask 95¢, mid 87.5¢. That mid says the YES side carries an implied 87.5% probability silver finishes above $70.99 on Friday. The options chain — pricing the same outcome through SLV — says 76%. NO contracts are trading near 12¢ when the model thinks they're worth closer to 24¢.

Sigma matters here. ATM SLV IV is 60% annualized. One-day silver standard deviation: $73.51 × 0.60 × √(1/252) ≈ $2.78. A drop to $70.99 from $73.51 is roughly a 0.9-sigma move with 1.3 days left — uncommon but not anomalous. Kalshi's 88% prices it as nearly locked in. Black-Scholes prices that exact move at 76%. The 12-point gap is the trade.

The other medium-confidence rows are far OTM strikes with wide bid-ask spreads — they show up as edges because options imply near-zero probability while Kalshi quotes show 11–12¢ residuals. Tradeable in principle, but I want to see the book depth before sizing on those.

Confidence Tiers and How to Read Them

Every row carries a confidence label. The thresholds:

• HIGH — edge ≥ 15pp AND tight two-sided book (spread ≤ 10¢) OR live volume confirms the print. Take the call.
• MEDIUM — edge ≥ 10pp with reasonable liquidity, or any edge with a wide spread caveat. Take it but verify the book before sizing.
• LOW — edge between 5pp and 10pp. Real but small after costs; size accordingly.
• PASS — edge below 5pp or the market has no executable book. Skip.
• SKIP — IV could not be back-solved (typically because the SLV strike is too far from the chain to interpolate).

Today's top call is MEDIUM, not HIGH. The edge magnitude is real but under the 15pp HIGH threshold, and I want a tighter book before aggressive sizing. That's the honest read.

The Hedge

If you want the directional exposure without single-source risk, the SLV options chain is the natural hedge. With today's $64.84 SLV price and 0.882 ratio, a Kalshi $70.99 silver strike maps to an SLV $62.59 strike. A May 1 SLV $63 put is the closest tradeable hedge.

One Kalshi NO contract pays $1 at most. One SLV option contract is 100 shares × roughly $5.65 of silver-equivalent notional per share at current ratios — so the hedge ratio is approximately 565 Kalshi NO contracts per one SLV $63 put for delta neutrality. Most retail traders run unhedged Kalshi positions and that's fine for sub-2% account sizing. The hedge is for traders running larger size who want to isolate the model edge from broad silver direction.

Position Sizing

Two rules I follow on every Silver Edge call:

1. 2% maximum per position. A single trade ties up no more than 2% of your trading account. The model is good but it's not god — silver has gapped 4–5% in single sessions during macro events. Keep size honest.

2. 5% combined cap on correlated strikes. If three strikes flag BUY NO on the same day, that's not three independent calls — it's one bearish silver thesis expressed three ways. Cap the combined notional at 5% of account.

This is also why I size off the contract cost (NO at 12¢, not the $1 max payoff). Kelly sizing on a +EV position with model uncertainty caps the optimal allocation well below the upper bound. If you want the math, the Kelly calculator does it directly — input the model probability and the contract price, get the size.

Caveats

Three honest constraints on the model:

1. Risk-neutral, not real-world. N(d2) is the probability the risk-neutral measure assigns to silver ending above K. The real-world probability is slightly different — there's a known risk premium gap on tail strikes that compresses real-world tail probabilities relative to risk-neutral. For the meat of the strike grid (within ±5% of spot) the gap is small. For deep OTM strikes ($89.99 today, 16pp above spot) the model edge can overstate the real edge. Those rows show up as MEDIUM with wide-spread caveats; I treat them as PASS until I see book depth.

2. SLV-to-silver tracking error. SLV tracks silver tightly but not perfectly. Daily tracking error is sub-0.1%; weekly is below the 5pp edge threshold. Long-horizon tracking can drift more. We're trading on weekly horizons where tracking is well below noise.

3. Settlement timing. Kalshi settles at exactly 5:00 PM ET on the Pyth XAG/USD print. Pyth is a network of price oracles with sub-second updates; the official settlement price is the print at the second crossing. If silver is moving sharply at the close, the exact print is luck. Build that into your sizing.

Use The Tool

The grid above is one snapshot from one day. The tool rebuilds it every morning at 6 AM Eastern from a fresh Pyth print and a fresh SLV chain. Pro subscribers get the full strike table, the daily Discord drop in #premium-alerts, and a public JSON API for embedding the snapshot anywhere.

Run the Silver Edge tool →

Same architecture rolls forward to gold, oil, and copper as Kalshi opens those weekly markets. The first commodity is silver because silver has the cleanest options chain and the deepest Kalshi book. The next one is whichever metal hits both bars next.

Two markets. Same underlying. The market that prices it wrong is the one paying you.