SVI Surface Parameters API

Endpoint

curl -H "X-Api-Key: YOUR_API_KEY" \
  "https://lab.flashalpha.com/v1/surface/svi/SPY"

import requests

resp = requests.get(
    "https://lab.flashalpha.com/v1/surface/svi/SPY",
    headers={"X-Api-Key": "YOUR_API_KEY"}
)
data = resp.json()
print(f"Front rho: {data['svi_parameters'][0]['rho']}")

const resp = await fetch(
  "https://lab.flashalpha.com/v1/surface/svi/SPY",
  { headers: { "X-Api-Key": "YOUR_API_KEY" } }
);
const data = await resp.json();
console.log("Front rho: " + data.svi_parameters[0].rho);

Response

{
  "symbol": "SPY",
  "underlying_price": 542.18,
  "as_of": "2026-06-05T14:32:10.123Z",
  "market_open": true,
  "svi_parameters": [
    {
      "expiry": "2026-06-20",
      "days_to_expiry": 15,
      "forward": 542.91,
      "a": 0.001204,
      "b": 0.142318,
      "rho": -0.612045,
      "m": 0.018221,
      "sigma": 0.094117,
      "atm_total_variance": 0.002918,
      "atm_iv": 16.42
    }
  ]
}

Key Response Fields

Errors

About

Returns the live SVI-fitted volatility surface for a symbol - the calibrated (a, b, ρ, m, σ) parameters per expiry slice, with ATM total variance and ATM IV. It is a lightweight subset of the full advanced-volatility payload for clients that reconstruct the surface themselves.

underlying_price is the mid of the underlying. svi_parameters is ordered by days_to_expiry; each slice gives the raw SVI parameters, the per-expiry forward, the ATM total variance, and the ATM implied vol as a percentage.

Common Use Cases

• Reconstruct the IV surface client-side - evaluate the raw (a, b, rho, m, sigma) per slice to rebuild total variance at any log-moneyness without re-fitting
• Price arbitrary strikes and expiries - interpolate off the calibrated svi_parameters[] slices and each slice's forward to value contracts not directly quoted
• Read skew and curvature - track rho for the skew sign and sigma for smile curvature across expiries to characterize surface shape
• Spot term-structure dislocations - compare atm_total_variance and atm_iv across slices to find a kinked or inverted front-to-back vol term structure
• Monitor calibration drift - snapshot the parameter vector over time and alert when b or rho jumps, signaling a re-shaped surface or a fit on thin quotes
• Feed a vol-arb or risk model - supply the calibrated slices as a compact, arbitrage-aware surface input to a relative-value or scenario engine

Related

Related reading

• SVI & curve fitting: building a modern IV surface - how the (a, b, ρ, m, σ) parameters shape each slice
• Engineering arbitrage-free volatility surfaces - the no-arbitrage constraints behind a calibrated surface

Complementary endpoints

• Advanced Volatility (SVI) - the full surface payload these raw parameters are a subset of
• Volatility - ATM IV and term structure without reconstructing the surface
• Skew Term Structure - read skew directly instead of deriving it from rho