Not sure of a definitive source that is reliable and accurate. Nowadays with all of the rampant corruptive practices such as naked short selling, it's hard to determine fundamentals. Price action used to be driven by supply and demand which in turn was affected by share structure, acquisitions, mergers...etc., but now the PPS just seems to be a number generated based on algorithms. There are so many layers of corruption in the markets, it's hard to tell where it begins or ends.
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