It depends. Among other things, it depends on how it's managed and what the occupants' expectations of sound-field are.  I cite trading floors -- I used to build them in NYC before the open-plan office idea started catching on big in the Bay Area. As far as I can tell, most people implementing open plan don't realize what they're getting into: 

[![enter image description here][99]][99]
[99]: https://i.sstatic.net/1rZSO.jpg


The whole point of open plan is communications<sup>2</sup> -- when Sally needs to get a piece of information to Bob 50 feet away, the fastest way for her to do that is to stand up and yell. Add hundreds of other sources like ordinary conversations, phone calls, and the always-on squawk boxes linking other floors worldwide by voice, dial all of them up to 11 as everyone tries to be heard over everyone else, and you have a continual roar. When something major happens somewhere in the world, you can actually hear it ripple through a trading floor, starting with the group(s) who are most immediately affected, spreading across the rest of the floor over the next few moments. This situational awareness is crucial<sup>4</sup>. 

*If* you want to have an organization that is that much of an agile machine, and *if* everyone on the whole floor signs on to work in a high-energy sprint or hackathon-like environment full-time, then it can work. It's hard to put numbers on it, but the revenue per headcount of the financial industry on average does tend to be higher than that of tech<sup>5</sup>.

Most open-plan offices I've seen in Silly Valley are instead expected to be as silent as libraries, and if any actual sound starts to emanate from one part of the floor, someone always pops up like a prairie dog to squelch it. It's never going to work that way -- a silent open-plan floor is an oxymoron and a productivity killer.  If Jimmy starts tapping his fingers three desks over, everyone gets distracted.<sup>1</sup>

By comparison, I used to go *to* the trading floor when I needed to hide and code -- the chaos of an unleashed open-plan environment is a sea of white noise, perfect for concentration, with plenty of ambient energy to keep you from drifting.

I'll do my best to find citations for these claims, but it's going to take time.  Much of what I describe above is just "generally understood" in the trading industry<sup>3</sup>, and most research about trading instead focuses on the instruments rather than the environment.  I welcome comments and edits, and I'll return here myself as I run across things in the future.

[1] It's easy to find papers that talk about the productivity losses from open-plan offices -- here's one of many that came up on the first page in Google, citing distracting sounds as being a main issue: http://www.sciencedirect.com/science/article/pii/S0272494413000340

[2] Here's an article that talks about open plan in general, how the noise can be distracting in general offices, but how the need for open plan on trading floors is still there, mentioning communications as a main benefit: https://jpreis.com/2017/12/05/2417/

[3] Trading's culture of open plan and expectations of a noisy environment date back to the days of open outcry pits: https://en.wikipedia.org/wiki/Open_outcry

[4] As more trading has moved from pits and open floors to small and remote offices, an entire industry has sprung up to stream floor sounds  over the internet to individual traders to give them that sound field gestalt that they would otherwise be missing. While this article's headline is about synthesized sounds, it also discusses some incidents where actual floor sounds mattered: http://www.post-gazette.com/business/tech-news/2006/06/14/Software-simulates-sounds-of-the-trading-floor/stories/200606140141

[5] It's hard to isolate out the benefit of open plan itself, but by industry, even in a challenging interest rate environment, the financial sector still eked out a 35% higher revenue/headcount ratio versus IT in 2016: https://craft.co/reports/s-p-500-revenue-per-employee-perspective