Given the input sentence, please extract the subject and object containing a certain relation in the sentence according to the following relation types, in the format of "relation1: word1, word2; relation2: word3, word4". Relations include: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

* Stock up 150 pct since resuming trade in June * Accounted for 45 pct of Dubai's June trading volume * Follows last year's bubble in Arabtec shares * Shows institutions still not influencing trade * Dubai more modestly valued than during Arabtec debacle By Olzhas Auyezov DUBAI, July 23 (Reuters) - A surge in shares of Amlak Finance since they returned to Dubai's stock market last month has raised concerns about a new wave of unbridled speculation on one of the region's biggest exchanges.

Answer: headquarters_location: Arabtec, Dubai