The UK financial regulators are locked in a quiet but high-stakes disagreement that could fundamentally change how much cash your favorite high-frequency trading firm or market maker has to keep in the bank. On one side, you've got the Financial Conduct Authority (FCA), which wants to make life easier for investment firms. On the other, the Bank of England (BoE) is worried that being too nice to these firms might actually break the financial system.
This isn't just bureaucratic bickering. It's a fight over the "Investment Firms Prudential Regime" (IFPR) and specifically how we calculate the "market risk" of firms that don't take deposits like high-street banks but still move billions in assets every single day.
The FCA Wants a Leaner Machine
Right now, many trading firms are stuck using capital rules that were basically copy-pasted from banking regulations. The FCA's recent engagement paper makes it clear they think this is a mistake. Their logic is simple: trading firms aren't banks. They don't hold your grandma's savings account, so if one of them goes bust, the taxpayer isn't immediately on the hook for a bailout.
The FCA is looking at several ways to "de-bank" these rules. One of the most popular ideas in the industry is the K-CMG method, which bases capital requirements on the margins that clearing houses already require. It’s a "pay for what you use" model. The FCA is also exploring a Net Capital Rule, similar to what the US uses. This would move away from complex Basel-style formulas and focus on one thing: does the firm have enough liquid cash to shut down tomorrow without causing a mess?
For the FCA, this is about competitiveness. If London is too expensive for trading firms, they’ll just move to Dubai or New York.
Why the Bank of England is Nervous
You’d think the Bank of England would want a competitive London, but they have a different job: stopping another 2008. Rebecca Jackson, an executive director at the BoE, recently called these trading firms "frenemies" of the banking system.
The BoE's concern is that these firms are now so big and so interconnected that their failure would be systemic. They might not have retail deposits, but they provide the "plumbing" for the entire market. If a major liquidity provider vanishes during a market shock because they didn't have enough capital to absorb losses, the whole system could seize up.
The BoE is effectively saying, "Just because you aren't a bank doesn't mean you can't cause a bank-sized disaster." They’re worried that the FCA’s push for "proportionality" is actually just a code word for letting firms take more risk with less of a safety net.
The "Systemic" Threshold Problem
The real battlefield is how we define a "systemic" firm. Industry groups like the Association for Financial Markets in Europe (AFME) are jumping into the fray. They’re arguing that the FCA shouldn't give a free pass to large proprietary trading firms just because they don't have customers.
AFME's stance is interesting because they represent the big banks. They're essentially calling for a level playing field. If a massive trading firm is doing the same kind of heavy lifting (and taking the same risks) as an investment bank, why should they get to hold less capital?
The industry is currently split into two camps:
- Small and Medium Firms: They want the FCA to win. They find the current rules expensive, confusing, and a total drag on growth.
- Systemic Giants and Banks: They want the BoE's tougher standards applied to anyone big enough to tip the boat.
What This Means for the Market
If the FCA gets its way, we'll likely see a "Primary Trading Firm" boom in London. Lower capital requirements mean more firms can enter the market, which usually leads to tighter spreads and better prices for everyone. It’s the "efficiency" play.
If the BoE wins, capital requirements will stay high—or even go up for the biggest players. This makes the UK market safer but more expensive.
Honestly, the middle ground is probably a two-tier system. We’ll likely see the FCA create a "Systemic Investment Firm" category that has to play by the BoE's stricter rules, while giving the smaller players the "Net Capital" or margin-based relief they've been begging for.
Your Next Steps
If you're running a firm or advising one, don't wait for the final rulebook.
- Audit your K-NPR vs. K-CMG: Start running parallel calculations now. If the FCA moves toward margin-based capital, you need to know if that actually saves you money or if your clearing house margins are already so high that it’s a wash.
- Review your "Systemic" footprint: Look at your market share in specific asset classes. If you’re a dominant player in a niche, the BoE has its eye on you regardless of your total balance sheet size.
- Engage with the FCA Roundtables: The regulator is actively looking for data to prove that lower capital doesn't mean higher risk. If you have the data, share it.
The deadline for feedback on the latest engagement paper was February 2026, and we're expecting a formal consultation later this year. This "stand-off" isn't going away, and the result will dictate the cost of doing business in London for the next decade. Keep your eyes on the PRA’s "near-final" rules on Basel 3.1, as that will be the benchmark the BoE uses to fight back against any FCA "weakness."
