Block Trades: Standalone and Off-ATM Mechanics

Introduction

A block trade is the fastest-clearing of the standard follow-on products: a single-clip overnight transaction where one or more banks purchase a large equity position from a holder (typically a PE sponsor, founder, or insider) at a negotiated discount and then redistribute the shares to institutional investors. The structure compresses the entire follow-on workflow into a few hours, prices through a competitive bid-wanted-in-competition (BWIC) auction, and is the dominant product for sponsor monetization of post-IPO positions and large insider sell-downs. Understanding standalone block mechanics, the off-ATM variant, the BWIC dynamics, and the bank's principal-risk decision is essential ECM knowledge because block trades are where junior bankers see the live tension between client relationship, principal commitment, and trading-floor execution most clearly.

The block trade workflow compresses the entire follow-on arc into roughly four to six hours, starting after market close.

The two principal block-trade structures differ in the legal infrastructure used to execute the transaction.

The Standalone Block

A standalone block is a self-contained transaction priced and documented in a few hours: the bank purchases the shares from the holder, files a prospectus supplement (if the holder is selling registered shares off a shelf), and the bank's accelerated bookbuild distributes the shares overnight. Standalone blocks are the dominant structure for sponsor sell-downs and are how most large secondary blocks clear in the US market.

The Off-ATM Block

An off-ATM block uses an existing at-the-market (ATM) equity distribution agreement as the legal infrastructure. Issuers with active ATM programs can execute a block off the existing agreement and prospectus supplement, eliminating the need for a separate filing. The structure is faster than a standalone block and works particularly well for primary issuance, especially during volatile windows where issuers want to clear meaningful tranches without fresh paperwork. Off-ATM blocks work best when the issuer has an active ATM, the transaction is primary, and deal size fits within remaining ATM capacity. Standalone blocks remain the structure of choice for selling shareholders, issuers without an ATM, or transactions exceeding available ATM capacity.

The competitive auction is what drives block-trade pricing, and understanding the BWIC dynamics is core to the ECM banker seat.

The BWIC Mechanic

A bid-wanted-in-competition is a controlled auction the seller (or their financial advisor) runs among two to four pre-selected banks, all of whom have signed confidentiality acknowledgments. Each bank receives the size and the deadline; bids come back over the phone or chat within a tight window, typically one to two hours. The seller then either picks the highest single bid or, if the position is large enough to justify a multi-bank trade, allocates the deal across two or three banks at the cleared price.

Bid-Wanted-in-Competition (BWIC)

A controlled auction format used to price block trades. The seller (or their financial advisor) invites a small group of banks to submit competitive bids for the position within a tight deadline, typically one to two hours after market close. Banks sign confidentiality acknowledgments before receiving deal details. BWICs are the standard pricing mechanism for standalone block trades and large off-ATM blocks because they extract maximum competitive tension within a confidential window.

Underwritten Bid Versus Variable Price Reoffer

Banks bid in two principal formats. An underwritten bid is a firm price commitment: the bank purchases the position at the bid price regardless of whether it can fully redistribute the shares overnight. A variable-price reoffer (VPR) bid sets a floor price (the bank's worst-case purchase price) and an indicative reoffer range, with the final transfer price set after the bookbuild based on actual demand. The VPR format reduces the bank's principal-risk exposure by sharing some of the downside with the seller, and it is more common on larger or more complex blocks where banks are unwilling to take full firm risk.

Variable Price Reoffer (VPR)

A block-trade pricing structure where the bank's bid sets a floor price (worst-case purchase price) and an indicative reoffer range, with the final transfer price set after the overnight bookbuild based on actual investor demand. VPR shares upside between bank and seller and is more common on larger or more complex blocks where banks are unwilling to commit to a flat firm bid.

What Drives the Bid Spread

The bank's bid is a function of several specific inputs: the position's size relative to typical daily volume (a large position relative to ADV will price wider), the borrow market for the stock (tight borrow makes hedging expensive and widens bids), the current institutional demand depth (strong demand tightens bids), and any catalyst risk in the overnight window (pending earnings or events widen bids materially). A tight bid usually clears at 3 to 5 percent below the closing price; a wider bid for a less-liquid position can clear at 6 to 10 percent discount or wider. In formula terms:

Single-Bank Versus Multi-Bank Blocks

For smaller block trades the seller typically awards the entire transaction to a single winning bank. For larger blocks (typically over $500 million) the seller may split the trade across two or three winning banks at the cleared price, with each bank running parallel accelerated bookbuilds against its own institutional account base. Multi-bank blocks expand the distribution capacity available overnight and reduce the residual-position risk any single bank holds, but they require careful coordination on the press release and allocation timing to avoid market confusion the next morning.

The Financial Advisor Role

Sophisticated sellers (especially PE sponsors monetizing large post-IPO positions) frequently retain a financial advisor (Lazard, Evercore, Centerview, Houlihan Lokey) to run the BWIC process on their behalf. The advisor's role is to maintain confidentiality across multiple bidding banks, draft the BWIC term sheet, evaluate the bids on a relative-value basis, and advise the seller on bank selection. Advisor fees are typically a small percentage of transaction value (often 25 to 50 basis points) and are economically efficient because the competitive tension the advisor extracts from the bake-off typically more than pays for itself in tighter cleared discounts.

Block trades sit alongside marketed follow-ons and overnight bought deals as alternatives in the secondary equity toolkit. The choice turns on holder identity, transaction size, and time pressure.

Why Block Trades Dominate Sponsor Sell-Downs

Private-equity sponsors monetizing post-IPO positions almost always prefer block trades because the structure offers speed (avoiding additional market-price risk between announcement and clearing), pricing certainty (the BWIC produces a firm cleared price), and discretion (no public marketing period signals a sell-down to the broader market until the block has cleared). The compressed timeline also fits sponsor exit calendars better than the 2-to-4 day marketed format because sponsors are often selling around earnings windows or fund-life deadlines that do not accommodate longer execution arcs.

A BWIC, an underwritten or VPR bid, an overnight accelerated bookbuild: the structure that lets a sponsor convert a billion-dollar position into cash by the next morning's open. When the issuer's need is the opposite, raising small tranches of primary capital continuously rather than monetizing a position in a single clip, the right product is a different one entirely. ATM programs are next.