The article is talking about stocks and private investing in companies. The current situation, both with the actions of the company and the current economic state of apartment buildings, is making the Surfers Paradise group more valuable as a stock option. This means it is more likely for investors to buy stocks in Surfers Paradise. The sentence only makes one connection between the infrastructure completion and the limited apartment supply: That they both improved the stock value of Surfers Paradise. "Complexes" refers to "apartment complexes," which is are multi-story buildings with multiple apartments on each floor.