Nasdaq has some service. They claim they make determination based on the publicly available data. I don't think I would trust this, but that's the closest I've found to resemble what you are looking for. https://www.nasdaq.com/press-releas...y-tracker-available-via-nasdaq-data-link-2021
%% TRUE but we would not mind knowing when Bill gates does many of his sells, WSJ noted those some time ago+ even that Billionaire seldom got the highest day $ price, much less\ highest penny. Speaking of sell ,MSFT, SCHW Market Edge has it a buy; trend analysis long term 200 downtrend, but sideways. IF i wanted max pain, try to penny time msft; even though Bill gates never pulled that penny time on MSFT/LOL[sarcasm]. Good thing for me i never want max pain Even the bigger + better players may or may not help some times; IBD weekly newspaper has them.
%% SPY= liquidity leader + has been for some time. Knowing Vanguard + SST.... have the major positions in AMZN may or may not help @ all. Even with an above average battle tested fund like Fidelity ContraFund =will not predict markets.
%% THEN study SPY; as much as you can+ then study it more to see why SPY= rightly called ''liquidity leader'' THAT would help you more, than any understandable words thru me. I write down SPY close price in addition to the study i just noted.
Yes but how does that answer my question: how does one test liquidity? I don't think I'd be satisfied with a "it touched resistance at £x.x then retraced so liquidity ended there" if that makes sense
%% IF you had studied SPY= liquidity leader; for sure that liquidity[price points] in SPY would prove what i'm noting. I was referring to all the data ./ You are right\2 data points[your example] tells us nothing. Liquidity is on the SPY charts+ bid\ ask spread+ time and sales+ somewhat in the SPY paper prospectus. I dont consider any test valid if its not on paper, or recorded on paper ; even if i used computer generated price points for paper recording. SPY liquidity does not ''end there'' in regular market hours; may get a bit thin @ market turns , but does NOT end . Dont confuse SPY with a mismanaged airline like DAL which went bankrupt \ended [ DAL liquidity was zero\bankrupt]
"Shows" from the remaining few floor brokers can sometimes give you tone. This has really become a major portion of their "added" value. Doing enough business to justify one is an issue. won't be of much help on stock dark pools or option hidden liquidity. Private feeds are a plus because they carry the info, often, well before it hits the tape, but again, you need to do a lot of business to justify the costs. A robust T&S source can also add a piece to the puzzle. None of it comes cheap and frequently the trade is only one piece of the overall trade.