Talk:Law of one price

Where is this from
"In an efficient market there is only one price." ... Where is this from? I do not recall market efficiency to be the unique determinant of no-arbitrage. Rather the efficiency talked about assures a zero-value epsilon in the bid-ask spread. Law of One Price is not about transaction costs, but about unique pricing and the absence of arbitrage. Right? So whoever added the "efficient markets" brackets should add some reference. Thanks. (Jerrey_Ward, 2009)

—Preceding unsigned comment added by Jerrey Ward (talk • contribs) 10:44, 1 February 2009 (UTC)

Royal Dutch Shell
"After merging in 1907, (...) This discrepancy disappeared with their final merger in 2005." I seriously doubt that a merger took more then one hundred years to complete. Rphb (talk) 18:52, 5 May 2012 (UTC)


 * You can read about Royal Dutch Shell: the merged group was formed in 1907 but legally remained two companies (Koninklijke Nederlandsche Petroleum Maatschappij and "Shell" Transport and Trading Company) until 2005 when the merger led to the creation of Royal Dutch Shell plc. More interesting for this article is instead of two shares whose prices should have remained locked together were not, two other shares have been created (RDSA and RDSB) each trading in two places and so now there are four prices which should be identical according to the law of one price but are not. --Rumping (talk) 17:54, 17 February 2015 (UTC)

No arbitrage
Isn't this the same as the No Arbitrage condition that quants speak of? 71.139.161.9 (talk) 21:17, 6 September 2014 (UTC)

comment
I know we're not supposed to write about the subjects per se here, but I can't stop noting that this "law" (not theory) is false -- or else the description has confused me. Even removing the stated exceptions, there are too many examples that I see all the time. If nothing else, valuation (as well as information) can substantially influence price. If most people in one location don't like, say, coarse bread because of the their upbringing, but people in another do, the prices are not likely to be the same unless some monolithic seller is "blindly" applying the same price. 64.53.191.77 (talk) 17:05, 18 May 2015 (UTC)

In particular "The law also need not apply if buyers have less than perfect information about where to find the lowest price." means that this law applies exactly nowhere in the real world. 66.62.244.4 (talk) 17:26, 10 June 2015 (UTC)