A Market-Structure Inflection: Rule 611, the SpaceX Lockup Wall, and the 24-Hour Race

Three structural forces are converging on global equity markets within a compressed six-week window — and the pattern they form is worth watching closely. The SEC has proposed rescinding the Order Protection Rule, the regulatory backbone of US equity trading since 2005. SpaceX, fresh off the largest IPO in US history, faces a lockup expiry beginning August 6 that could release more than $117 billion in shares. And the London Stock Exchange has announced plans for a 24/5 trading venue, accelerating a global race toward round-the-clock markets. Each is significant in isolation. Together, they amount to the most concentrated burst of market-structure change in years.

1. The SEC moves to unwind Rule 611

At an SEC open meeting on June 11, 2026, Chairman Paul Atkins said he had opposed Rule 611 — the Order Protection Rule at the heart of Regulation NMS — since its adoption in 2005, arguing that rather than encouraging displayed liquidity, it had helped drive the spread of trading venues and left the market more fragmented, costly, and opaque^[1]. The agency has now formally proposed rescinding the rule, a step that would mark one of the most consequential changes to Regulation NMS in two decades^[1].

The argument for repeal is gaining traction among institutional traders. Mett Kinak, global head of equity trading at T. Rowe Price, told the Security Traders Association of New York that the order protection rule had become redundant in a market far more automated and interconnected than the one in which it was created^[1]. He argued the rule no longer reflects how trading actually works and has, in practice, protected commercial venues at the expense of market users by forcing brokers to connect to every protected quote^[1].

But Kinak also flagged the core risk: if protected quote status disappears, firms could begin relying on different data feeds to calculate their own versions of the best bid and offer, fragmenting the market further rather than consolidating it^[1]. He proposed a market-share threshold for participation in the Securities Information Processor, so that only substantial venues would contribute to a standardised benchmark^[1]. The NBBO, he argued, would remain essential for transaction cost analysis and best-execution review even without trade protection^[1].

The broader question is how rescinding Rule 611 would affect best-execution obligations. Many buy-side firms have treated compliance with the rule and compliance with best execution as overlapping concepts. A move to a non-protected framework would require a more principles-based compliance approach — though brokers’ fiduciary duties should limit abrupt changes in routing behaviour^[1].

What makes this worth flagging now is the timing. A rule rescission would not happen overnight, but the formal proposal itself changes the calculus for every venue operator, market maker, and routing committee that has built infrastructure around protected quotes. The signal is directionally clear: the SEC is moving toward a framework where competition and data, rather than the trade-through prohibition, govern execution quality.

2. SpaceX’s lockup wall arrives August 6

SpaceX (NASDAQ: SPCX) went public in early 2026 in the largest IPO in US history, raising more than $29.4 billion^[2]. The company is set to report its first earnings as a publicly traded company on August 4^[3]. Two days later, on August 6, the first lockup tranche expires: 20% of locked-up stock, roughly 911.5 million shares, enters the tradable float^[3].

At the IPO price of $135, that tranche alone would be worth approximately $123 billion^[2]. At the July 21 trading price of about $128.97 — already below the IPO price — the same shares are worth roughly $117.6 billion^[3]. An additional 10% tranche, about 455.8 million shares, could unlock on the same date, but only if the stock trades at least 30% above the $135 IPO price (i.e., above $175.50) for at least 5 of 10 consecutive trading days ending on the earnings release date^[3]. With SPCX trading near $129, that condition is nowhere close to being met^[3].

Further tranches follow in quick succession: approximately 319 million shares (7%) around August 21, and another 319 million shares (7%) on September 10^[3]. Currently, only about 555 million shares — roughly 5% of the 13 billion total — are in the public float^[3]. Elon Musk’s 6.4 billion shares remain locked until June 2027 with no early release provisions^[3].

The stock has already fallen roughly 47% from its post-IPO high^[4] and was trading near $131, an all-time low for its brief public life^[2]. A Starship launch abort added to the pressure^[2]. The pattern to watch is straightforward: the August 6 unlock multiplies the tradable float by a factor of roughly 2.6 in a single session, against a stock already trading below its IPO price. Historical lockup expirations typically produce a drift toward selling pressure over the following 30 to 60 days, but the scale here is unprecedented. No single issuer has ever faced a supply shock of this magnitude this quickly after going public.

3. London goes 24/5 — the global trading-day race

On July 21, the London Stock Exchange announced plans to launch LSE 24, a new 24/5 trading venue designed for near-continuous trading from Monday to Friday^[5]. The venue will operate from 17:00 to 07:50 with a 30-minute pause for end-of-day processing, running separately from the Main Market, which will continue its existing 08:00–16:30 hours^[5].

Client testing is scheduled for the end of 2026, with exchange-traded products as the first asset class launching in H1 2027, subject to regulatory approval^[5]. The venue will draw on central limit order book and request-for-quote functionality, with plans to expand into equities as the next step^[5]. Julia Hoggett, CEO of LSE plc, called the launch “an important step in the evolution of our markets,” emphasising deeper liquidity and broader participation^[5].

The move places London in a competitive race that already includes US exchanges exploring extended-hours trading and a growing chorus of market participants arguing that the traditional trading day no longer serves a globally distributed investor base. But the signal here is not just about convenience. A 24/5 venue built for “algorithmic and agentic trading”^[5] implicitly assumes that liquidity will be available around the clock — and that market participants will staff or automate risk management continuously. For institutional desks, that raises questions about staffing, overnight risk controls, and the cost of maintaining competitive quoting during thin overnight sessions.

The LSE is starting conservatively with ETPs, which makes sense — ETPs are a natural testing ground for extended-hours liquidity because they are less susceptible to the information asymmetries that make overnight single-stock trading risky. But the trajectory is clear: if ETP volumes materialise, equities will follow, and the pressure on US exchanges to match will intensify.

Korea’s leveraged-ETF crisis: the warning pattern

While the SEC considers deregulation and exchanges extend trading hours, South Korea offers a cautionary case study in what happens when market-structure innovation outpaces risk controls. On July 16, Korean financial authorities halted new listings of single-stock leveraged ETFs — products tied to Samsung Electronics and SK hynix that had become key drivers of market volatility^[6]. The government tripled the basic margin deposit and required full cash payment for leveraged ETF positions^[6].

The measures came after an estimated 1.2 million margin calls were triggered as the KOSPI plummeted from record highs^[6]. President Lee Jae Myung ordered supplementary measures on July 21, criticising the slow response and demanding stricter rules^[6]. But experts have criticised the government’s actions as band-aid fixes, calling for structural reforms including futures-based hedging and averaged settlement to reduce the end-of-day concentration of rebalancing trades^[6].

The Korean episode is relevant to the broader market-structure picture for a specific reason: it demonstrates how a product designed to provide efficient leveraged exposure — a single-stock leveraged ETF — can become a systemic volatility amplifier when its rebalancing mechanics concentrate trading into the closing auction. That same dynamic, at a smaller scale, is what the SEC’s Rule 611 debate is partly about: whether regulatory architecture is keeping pace with the products and trading behaviours it governs.

The IPO pipeline: data centers, biotech, and pricing discipline

The US IPO calendar shows a market that is open but exercising caution. Csquare (NASDAQ: CSQR), a data center operator with 64 facilities across the US and UK, raised $1.1 billion by pricing 50 million shares at $21 — below its $23–$27 range^[7]. The below-range pricing for a data-center infrastructure name is a quiet signal: even in a sector broadly favoured by AI-driven demand, investors are not paying top-of-range for new issuance.

Scribe Therapeutics (NASDAQ: SCTX), a Phase 1 biotech developing CRISPR therapies for cardiovascular diseases, set terms for a $100 million IPO^[7]. The biotech pipeline also includes Braveheart Bio (BRVE) and Attovia Therapeutics (ATTO), both targeting $100 million deals^[7]. A SPAC, Southern Cross Acquisition I Corp. (NCOU), is also on the calendar with a $100 million target^[7].

Meanwhile, lockup expirations from earlier 2026 IPOs continue: BitGo Holdings (BTGO) saw its lockup end July 21, and EquipmentShare.com (EQPT) on July 22^[8]. These are smaller in scale than the SpaceX unlock but add to the aggregate supply overhang.

What to watch next

The three signals — regulatory, supply, and competitive — do not need to produce a single dramatic event to matter. The pattern to watch is the accumulation: a market simultaneously rewriting its execution rules, absorbing the largest lockup expiry in history, and extending its trading day to 120 hours a week. Any one of these would be a normal market-structure story. All three arriving within the same quarter is the anomaly worth tracking.