Errrmmm, sure - the "halfway point" for the data between New York and London is "in the middle of the ocean", but floating above it in a boat isn't going to give you access to the fibers down ion the ocean floor.
I call bullshit.
I call bullshit.
It's crazy for lots of other reasons (the expense of doing something like this, the zero sum nature of it, and the easy solution of just having "tick based" trading where all trades submitted in a given interval are randomly selected from to happen at a certain time), but doesn't seem technically infeasible.
Just like "factorising large prime numbers" is the easy (to ask for) solution to other problems.
I think the truth is, unless you've got enough money to run your own trans Atlantic optical fibers, either with your center-tap coming up to your mid-ocean floating datacenter, or with some as-yet-un-invented unmanned deep sea datacenter sitting on the ocean floor in the middle of your private fiber - this is pretty much an "I want a pony!" solution to reducing transaction times.
I don't see how radio helps much?
(perhaps a string of line-of-sight high frequency repeating stations? At a first approximation assuming 100m (330') tall towers you get ~36km to the horizon, so you'd need ~150 towers with repeaters on them to cover the ~5500km from London to New York. I guess that's not _impossible_, but even if you could stack up the infrastructure required, the latency in those ~150 repeaters would need to be very small to beat the guy sending his data through the fibre on the sea floor with a theoretical ~20ms ping time, and a quickly googled practical pingtime of ~100ms. The radio options still requires the ~20ms speed-of-light propagation time, but needs to get the signal through ~150 repeaters as well, compared to just the one on each end of the fibers (I _think_ the optical repeater/amps used on oceanic fibers are zero latency...)
AWACS – or analogous commercial aircraft regularly in convenient positions?
Or far fewer towers/tethered-transmission-balloons at much higher altitudes?
Or even unmanned constantly-flying communications platforms – 'SkyStation' was one such blimp-based concept from the 90s.
Wikipedia suggests the actual service distance from an elevated antenna is a bit larger than the simple geometric estimate. Also, I think you've doubled the necessary number of 100m-high relays: if each tower reaches the horizon at N kilometers, they reach another equivalently-elevated tower at 2N kilometers.
Seriously, though, if there was something to this, they could eventually splice some optimally-positioned platforms into transatlantic cables (existing or new). Of course then the 'optimal position' would then be more a function of available cabling than of natural geometry/geography.