As stated in my original post, I don't know if I can use the pivot because it only seems to work by aggregating, eg using count or max etc, I...

Is using Row_Number a good way to do this?

Such as

WITH TradersTable AS (

SELECT ROW_NUMBER() OVER (PARTITION BY TradeId ORDER BY Type) AS RowNum,

T.Id,

TraderId,

Type

FROM Trades T

LEFT JOIN MapTradesTraders MTT ON...