FinancialData and disjoint result sets from range and Month

*To*: mathgroup at smc.vnet.net*Subject*: [mg99794] FinancialData and disjoint result sets from range and Month*From*: N <enoman.nr at gmail.com>*Date*: Thu, 14 May 2009 02:05:17 -0400 (EDT)

I have a puzzle, probably easily explained; apparently so easily that it hasn't even appeared here. >From examples in the Mathematica ref/FinancialData: Give the monthly highs for a stock price over a range of dates: FinancialData["GE", "High", {{2005}, {2006}, "Month"}] High is defined as: High: Highest price during the trading day My guess, then, is that the source set is all intraday prices for from start {2005,1,1} until end {2006,1,1}. Consequentially I expect that there will be an intersection for January between that result and this result: FinancialData["GE", "High", {{2005, 1, 1}, {2005, 2, 1}}] There is not. The maximum for the date range: Map[#[[2]] &, FinancialData["GE", "High", {{2005, 1, 1}, {2005, 2, 1}}]] // Max = 31.2038 While from the earlier "Month" query we have = {{2005, 1, 3}, 31.2028} If one considers that the date-range version might have a superset of times, and the high occured in that interregnum, then comparing March's result will disappoint: the opposite occurs (the high appears in the "Month" result). If one wishes to explain this by precision effect during calculation, although I find that dubious, consider that FoldList[] on "Return" will produce what "CumulativeReturn" delivers. So, what's the simple explanation? Thanks, --N