The Great Supply Test: Lockups, Buybacks, and the Biggest Market-Structure Rewrite in 20 Years

Three quiet indicators have been building in parallel since June, and they are now converging into what may be the most significant test of US equity-market supply and plumbing in a generation. None of them is a crisis on its own. Together, they form a pattern worth flagging early.

The first signal: the largest IPO in history is about to face a lockup unlock larger than its entire public float. The second: the corporate buyback bid that underpinned equity demand for a decade is being redirected into AI capital expenditure at the same moment equity issuance is surging. The third: the SEC has proposed rescinding the core rule that has governed how US stocks trade for two decades. Each has a different timeline, but the overlap is the story.

Signal One: SpaceX’s $123 Billion Lockup Unlock

SpaceX (SPCX) raised a record $75 billion in its June 11 IPO, pricing at $135 per share.{{cite:00cd52fb6e95}} The IPO made less than 5% of shares available for public trading, creating a scarcity-driven valuation that briefly pushed the company’s market cap above $2.1 trillion on its first Nasdaq day.{{cite:00cd52fb6e95}}

That scarcity is about to change — dramatically.

On the second trading day after SpaceX’s first quarterly earnings report, expected in early August, 911.5 million shares held by rank-and-file employees and some early investors become eligible for sale. Those shares are currently worth approximately $123 billion — more than the $86 billion worth of shares currently trading on the Nasdaq.{{cite:00cd52fb6e95}}

The lockup structure is unusually phased. Unlike the standard 180-day cliff that governs most IPOs, SpaceX built in staggered release valves:

• Post-Q2 earnings (early August): Up to 20% of eligible locked-up shares unlock. An additional 10% unlocks if the stock trades at least 30% above the $135 IPO price ($175.50) for five of ten consecutive trading days through the earnings date.{{cite:49a5741d08c4}}
• Rolling schedule: Additional 7% tranches unlock at 70, 90, 105, 120, and 135 days post-IPO.{{cite:49a5741d08c4}}
• Post-Q3 earnings (approximately October): An additional 28% of eligible shares can be sold.{{cite:49a5741d08c4}}
• 180-day mark (approximately December): Remaining restricted shares are fully released, except Elon Musk’s stake, which remains locked until mid-2027.{{cite:49a5741d08c4}}

By December 8, restrictions lifted through that date will have increased SpaceX’s potentially tradeable float to 40% of the company.{{cite:00cd52fb6e95}}

The stock has already been signaling stress. Shares dipped as low as $132.15 on July 16 before closing at $135.27 — below the IPO price — and traded down further on July 17 to near $131.{{cite:00cd52fb6e95}} The stock is down approximately 33% from its record close in the days after the IPO.{{cite:00cd52fb6e95}}

A Reuters analysis of 50 high-profile US IPOs since 2010 found that companies whose shares fell below their IPO price in the first two months of trading went on to underperform those that did not, with a median post-debut gain of 61% versus 112% for the group that held above its IPO price.{{cite:00cd52fb6e95}} Of the 50 companies studied, 21 fell below their IPO price within two months — a cohort SpaceX has now joined.

The structural complexity here is unusual. The first post-IPO earnings report is simultaneously a fundamental catalyst and a supply event — two things that are normally separated by months. Insiders, passive index funds forced to buy at inclusion, and discretionary investors all face the same calendar window, with different incentives.

Signal Two: From Buybacks to AI Capex — the Bid That’s Fading

The second signal is quieter but potentially more consequential for the broader market. The corporate buyback bid — a primary source of equity demand since the post-2009 bull market — is weakening at the same time that equity supply is surging.

Fidelity’s Jurrien Timmer noted in June that buybacks and dividends are declining as a percentage of earnings amid a surge in capital expenditures, signaling what he described as a potential end to the buyback era that drove much of the secular bull market.{{cite:7b5d3ff35c64}} While absolute buyback announcements remain near record levels in nominal terms — Corporate America has announced roughly $1 trillion in stock buybacks in 2026 — the growth rate has decelerated meaningfully, and buybacks as a percentage of market cap have slid to their lowest level since late 2023, according to Bank of America Global Research.{{cite:a658568aba26}}

The divergence is starkest in technology. J.P. Morgan Asset Management’s David Kelly reported that tech hyperscaler repurchase activity is down 64% year-over-year, even as capex for AI infrastructure reaches unprecedented levels.{{cite:a658568aba26}} The pattern is clear: capital that would have retired shares is being redirected into data centers, GPUs, and compute capacity.

Wall Street Horizon data shows global buyback announcements are close to their weakest nominal amount since before the pandemic — a striking contrast to the 2020-2021 golden age of repurchases driven by near-zero borrowing costs.{{cite:a658568aba26}}

Meanwhile, equity supply is rising sharply. On June 1, Alphabet (GOOGL) announced an $80 billion equity capital raise to fund AI infrastructure, later upsized to $84.75 billion, including a $10 billion private placement by Berkshire Hathaway.{{cite:61abab8d102c}} The underwritten portion was oversubscribed.{{cite:61abab8d102c}} That single secondary dwarfs most IPOs and represents a fundamental shift: one of the world’s most valuable companies is issuing equity rather than retiring it.

The Interactive Brokers / Wall Street Horizon analysis frames the emerging question plainly: as more equity supply hits the market through secondaries and IPOs in 2026, will the corporate world still be there as a major buyer? The buyback bid that absorbed supply in past cycles may be in jeopardy.{{cite:a658568aba26}}

This is not a binary deterioration. Buybacks remain substantial in absolute terms, and non-tech sectors — Financials and Energy — have picked up repurchase activity.{{cite:a658568aba26}} But the composition shift matters: the largest companies by market cap are the ones pulling back from buybacks, and they are the same ones issuing the most new equity.

Signal Three: The SEC Proposes Rescinding Reg NMS Rule 611

On June 11, 2026 — the same day SpaceX priced its IPO — the SEC proposed rescinding Rules 611 and 610(e) of Regulation NMS, the framework that has governed US equity trading since 2005.{{cite:ac18994cff14}}

Rule 611, the trade-through rule, requires trading centers to prevent executions at prices inferior to protected quotations displayed at other venues. Rule 610(e) prohibits locked and crossed quotations. Together, they form the architecture that ensures an order routed to one exchange cannot be filled at a worse price than what is displayed at another.

SEC Chairman Paul Atkins called the proposal a response to “unintended consequences that have hindered — rather than enhanced — the long-term growth of our markets,” stating the goal is to “simplify market structure and reduce costs for market participants while allowing competition, innovation, and other market forces to shape the continuing evolution of our equity markets.”{{cite:ac18994cff14}}

The Skadden analysis describes the proposal as “one of the most significant changes to U.S. equity market structure since the adoption of Regulation NMS.”{{cite:8c93afa911bf}} Key implications include:

The public comment period remains open for 60 days following Federal Register publication.{{cite:ac18994cff14}} The Commission has requested comment on whether best-execution requirements should be updated, whether access fee caps should be revised, and what transition framework would be appropriate.{{cite:8c93afa911bf}}

Notably, the proposal’s release briefly references crypto assets and distributed ledger technology, noting that emerging tokenized-securities markets may raise “challenges and questions relating to current equities market structure.”{{cite:8c93afa911bf}} While the SEC did not explicitly state that tokenization drove the rescission, removing Rule 611 would eliminate a requirement that is particularly difficult to apply across trading venues that are not interconnected in the same way as traditional equities exchanges.

Why the Convergence Matters

The three signals are distinct events with different timelines, but they share a common thread: each, in its own way, changes the supply-demand equation for US equities.

The SpaceX lockup unlock adds a potential $123 billion of supply to a float that currently holds only $86 billion in tradeable shares — and it arrives alongside the company’s first earnings report, fusing a fundamental catalyst with a supply event.{{cite:00cd52fb6e95}}

The buyback-to-capex shift removes a structural demand bid from the market. If the pattern that Wall Street Horizon and Bank of America identify continues, the corporate sector will be a net issuer of equity rather than a net retiree of it — the inverse of the dynamic that prevailed for most of the post-2009 bull market.{{cite:a658568aba26}}

The Reg NMS rescission, if adopted, would change how every US stock trades — not just new listings. The proposal’s 60-day comment window and the Commission’s explicit request for input on transition mechanics mean the final rule could differ materially from the proposal.{{cite:8c93afa911bf}} But the direction is clear: the SEC wants to let market forces, rather than a prescriptive rule, determine execution quality.

The IPO calendar itself is thin in the immediate term. Renaissance Capital’s calendar shows no scheduled IPOs for the week of July 13 or beyond,{{cite:34174f91b981}} while IPOScoop lists a handful of small deals priced in mid-July: Csquare (CSQR) at approximately $1.05 billion, Standard Nuclear (STDN) at $150 million, and AMR Resources Acquisition (AMACU), a SPAC, at $250 million.{{cite:f43573f162a6}} Stock Analysis shows only Southern Cross Acquisition I Corp. (NCO), another SPAC, scheduled for the week of July 21.{{cite:f25946343e5c}} The pipeline is quiet — but the backlog of potential mega-offerings (Anthropic, OpenAI) looms for the back half of 2026.{{cite:a658568aba26}}

Other lockup expirations are also in motion. Briefing.com’s calendar shows BitGo Holdings (BTGO) lockup ending July 21, EquipmentShare (EQPT) on July 22, and additional names through late July.{{cite:e5c8ecb318fe}} None approaches the scale of SpaceX, but they add to the incremental supply picture.

What to Watch Next

• SpaceX Q2 earnings (expected early August): The first earnings release as a public company. Revenue trajectory, Starlink subscriber growth, and AI segment losses are the fundamentals. The lockup mechanics that activate on the second trading day after this release are the supply event. Watch both simultaneously.
• SPCX price level versus $175.50: If the stock trades above $175.50 for five of ten consecutive trading days through the earnings date, an additional 10% of eligible shares unlock on top of the base 20%.{{cite:49a5741d08c4}} At current prices near $131, that performance threshold appears distant — meaning the base 20% tranche is the relevant unlock to model.
• Reg NMS comment period close: Comments are due 60 days after Federal Register publication. The volume and tenor of industry feedback will signal whether the proposal survives substantially as written or faces significant revision. Watch for exchange comments, wholesaler comments, and investor-advocacy responses.
• Q2 2026 earnings season buyback activity: The IBKR / Wall Street Horizon analysis flags buyback announcements as an emerging earnings-season story.{{cite:a658568aba26}} If S&P 500 companies announce fewer repurchase authorizations during Q2 reporting season — particularly among mega-cap tech — the buyback-scarcity thesis strengthens.
• Alphabet equity raise follow-through: Alphabet’s $84.75 billion raise priced with minimal market disruption (the stock “hardly budged”),{{cite:a658568aba26}} but the absorption test comes over quarters as the new shares settle into float. Additional mega-cap equity raises for AI infrastructure — whether from Alphabet, Amazon, Microsoft, or Meta — would confirm the issuance trend.
• IPO pipeline for H2 2026: The current calendar is thin, but the potential Anthropic and OpenAI offerings would add tens of billions in new equity supply if they materialize.{{cite:a658568aba26}} Monitor S-1 filings and press reports for timing signals.
• Corporate insider selling trends: The Morningstar/MarketWatch analysis (cited in search results) flags that even as companies announce $1 trillion in buybacks, insiders are selling — a divergence worth tracking through SEC Form 4 filings during earnings season.{{cite:7b5d3ff35c64}}

The base case is that markets absorb the incremental supply without a structural break — corporate cash flows remain strong, earnings are growing, and the buyback bid, while diminished, has not disappeared. But the pattern that warrants early attention is the simultaneity: a record lockup flood, a secular shift in corporate capital allocation, and a regulatory rewrite of trading rules all arriving within a narrow window. Each is manageable alone. The question is whether the system can absorb all three at once.

This article is research commentary, not investment advice. No trades are placed and no account is managed here. Data is sourced from public filings, exchange filings, and cited news reports current as of July 18, 2026.