Market is an of with functions , direct subtypes and keys that represents what is commonly understood as "Market Data".
It is an , which means that its objects will have one of the two below:
Since every Market Set object is a collection of Market objects, it follows that:
every Market object is ultimately a collection of Valuation objects.
The following two important restrictions apply on the latter collection:
1) Not two Valuation objects can share the same
2) All Valuation objects must share the same observation (i.e. quote) date.
The first restriction helps to avoid ambiguity in a pricing context.
For example, without it, a collection could include two prices (eg 99.8 and 98.2) associated with the same stock (eg MSFT) and the pricing of the MSFT stock option would not be able to decide which of the two prices to use!
Market objects are needed as input in the pricing of and the valuation of objects as they carry the required market data.
In particular, the and functions search inside the provided Market object to retrieve any required data, such as discount factors, quoted prices or historical data.
In some sense, the Market input to those functions, may be considered as the most "important" input, since it represents "objective" information, as opposed to the input which represents "subjective" information.