I'm basically looking at this chart:
At first glance, I'm not sure it's clear as to why excess liquidity (money supply growth less GDP growth) is charted a whole 12 months ahead in the series. I could only assume it had something to do with contracts and other legal frictions. However, I think most supply chains and other real-economy type of contractual arrangements are longer than one year -- at least historically. Plus not all contracts are on the same date; contracts are beginning and ending all the time, so maybe it's not about contracts at all. Ergo I would like to explore the justifications for excess liquidity to be pushed forward 12 months -- and why 12 in particular. To me, it just seems a bit spurious, but that's perhaps because I don't have the intuition just yet.
What is the justification for excess liquidity being a leading indicator of market performance, and a lengthy 12-month one at that? (I understand the context of chart design, makes it look nice, but there should be some theory that underpins the aesthetics/correlation when we move the series 12 months forward).