Arbitrage in a "single market", which your definition implied, no longer exists. That used to happen b/c of the lack of RTI and computerized trading (inefficiancy) that caused mispricing.
Arbitrage opportunities today mainly involve MULTIPLE markets and/or instruments in the real world because of price discrepancies/differences and has NOTHING to do with inefficiancy.
Forex, like where $1CAD is worth $1.02 USA which is 46 PHP which = $1.05 CAD.
Sports Betting. Bovada offers Misty/Kerry at +400 to win the V-Ball. Bookmaker offers them at even money to lose. You play the middling position of Bovada at $200 to win $800 and Bookmaker at $400 to win $400 you guarantee yourself $200 on one position and $400 on another.
Or the hedges.....Buffett shorting housing while selling bundled housing instruments being something relatively well known.
Some kid buys a Pujols rookie for $10 from his neighbor. Then he sells it to a card shop for $50. ARB situation in a microecon setting.
Main point being ARB involves MORE THAN ONE market. The kid valued it at $10 and bought it there. The card shop valued it at $50 so he sold it there. Bovada thought Misty/Kerry was the 3rd best option to win the tourny, Bookmaker thought they were 50/50 to lose. PHP values US dollars more than CAD. CAD buys more USD.
All a long way of saying ARB cannot exist in "the market" (need 2). Also, inefficiancy = zero relevance today. HSX may use trailing avg but the real world is real time and 24/7.
It also didn't change the HSX usage which was the main point. So you're essentially confusing that point for the person that was asking for how it was used....he didn't say directly but it should be assumed he asked for ARB's use here.
And I don't see anything wrong with saying ARB in HSX is when a security here is priced below its real world counterpart.....in his specific example for delist purposes.
The only part of my definition that was "correctable" was saying 2 markets. My bad, was thinking HSX. Still, my definition correct....your whatever-pedia answer....not so much.