{
    "topic": "indexprice@SPOT_ETH_USDT",
    "ts": 1618820361552,
    "data": {
        "s": "SPOT_ETH_USDT", // symbol
        "px": "3987.1",       // index price
        "ts": 1618820361552   // timestamp at which the index price was calculated
    }
}

​
Topic: indexprice@{symbol}

Push interval: 1s
Subscribe to the index price of the symbol. 
{
    "topic": "indexprice@SPOT_ETH_USDT",
    "ts": 1618820361552,
    "data": {
        "s": "SPOT_ETH_USDT", // symbol
        "px": "3987.1",       // index price
        "ts": 1618820361552   // timestamp at which the index price was calculated
    }
}