This endpoint provides Market Index Data received from NGESO. Market Index Data is a key component in the calculation of System Buy Price and System Sell Price for each Settlement Period. This data is received from each of the appointed Market Index Data Providers (MIDPs) and reflects the price of wholesale electricity in Great Britain in the short term markets. The Market Index Data which is received from each MIDP for each Settlement Period consists of a Market Index Volume and Market Index Price, representing the volume and price of trading for the relevant period in the market operated by the MIDP. The Market Price (the volume weighed average Market Index Price) is used to derive the Reverse Price (SBP or SSP).