It has been my understanding that CDS and CDS indices are traded in the OTC market. Surely, this would mean that if an investor decides to go long a CDS contract, the spread that the investor will be paying will not be public on the market i.e. it will be known only to the investor and the trader who did the transaction.
Then how is it possible that we can actually see the spreads time series (say on bloomberg for example) for a CDS. Does it represent the level at which the last CDS trade was conducted?