Airballoons or airships could be very useful for building wireless communication across oceans (Transatlantic).
2013 (Poular Science): Microwave Balloons Could Form New Super-Fast Transatlantic Trading Line "Perseus Telecom, a network provider that specializes in rapid trading, is seriously looking into an ultra-high-speed transatlantic trading line, made possible by balloons and microwave transmission.”
2013 (WSJ blog): Enduring Quest for Superfast Trading Takes to the Air
2013 (blog): Can balloons really enable HFT, or is it just hot air?
The future Transatlantic communication for his speed trading is likely through air and or hollow core fiber along the ocean floor, neutrino communication through earth is also an interesting alternative.