What are fails-to-deliver (FTD) for BIIB?

A fail-to-deliver happens when a trade in BIIB isn't settled by the delivery date — the seller doesn't hand over the shares on time. The SEC publishes the aggregate number of BIIB shares that failed to deliver on each settlement date. The latest published figure is 104.00 shares (settled 2026-06-03).

Does a high FTD mean BIIB is heavily shorted?

Not directly. Fails-to-deliver is a settlement metric, not short interest — fails arise from mechanical settlement issues, market-making, and long as well as short sellers. A persistent, large fail relative to a name's own history can be worth noting, but FTD alone is not a measure of how shorted a stock is.

How often is BIIB FTD data updated?

The SEC releases fails-to-deliver data twice a month — one file for the first half of each month and one for the second — with a lag. Settlement itself is T+1 (the business day after the trade). Under Regulation SHO, participants must generally close out short-sale fails by the next settlement day (longer windows exist for long sales, bona-fide market making, and certain deemed-to-own securities), and names with large persistent fails can join the exchange threshold-security list after 5 consecutive settlement days. This page rebuilds as new files publish.

Is BIIB's fails-to-deliver a buy or sell signal?

On its own, no — FTD is context, not a verdict. Our current SEC-grounded rating on BIIB is HOLD, based on the company's filings rather than settlement mechanics. Use the fails history as one input alongside the fundamentals.

Fails-to-deliver · SEC settlement data

BIOGEN INC. (BIIB) fails to deliver

Our ratingHoldB-

Latest fails

104.00

settled 2026-06-03

Peak in window

516.00

2026-05-22

vs trailing median

0.9×

In line

Latest value

$19.6K

qty × SEC prior close

Fails-to-deliver over time

7 settlement prints · shares failed

peak latestQuantity only — no price data on the chart.

Fails-to-deliver history

BIIB fails-to-deliver by settlement date, from SEC data
Settlement date	Shares failed	SEC price	Approx. value
2026-06-03	104.00	$188.83	$19.6K
2026-05-27	97.00	$193.08	$18.7K
2026-05-26	6.00	$193.76	$1.16K
2026-05-22	516.00	$189.47	$97.8K
2026-04-30	16.00	$194.38	$3.11K
2026-04-17	122.00	$176.02	$21.5K
2026-04-16	153.00	$180.54	$27.6K

How to read this data

What a fail is. A fail-to-deliver occurs when the seller in a trade doesn’t deliver the shares by the settlement date. The figure here is the aggregate number of shares of BIIB that failed to deliver on each settlement date, as reported by the SEC.
Settlement is T+1. US equities settle one business day after the trade (T+1 since May 2024), so the settlement date shown is one business day after the trade that failed.
The SEC publishes twice a month. Fails data is released in two files per month — the first and second halves — on a lag, so the most recent settlement dates appear only after the next publication.
Reg SHO close-out. Participants must generally close out short-sale fails by the next settlement day after they arise (longer windows apply to long-sale and bona-fide market-making fails, and a 35-calendar-day window only to certain deemed-to-own securities). Names whose fails stay large for 5 consecutive settlement days join the exchange threshold-security list, which brings stricter close-out duties — so persistent large fails are the exception, not the norm.
Not short interest. Fails arise from settlement mechanics and market making as well as short selling, and are not a direct measure of how heavily a stock is shorted. The SEC price column is the prior-day closing price the SEC ships in the same file — we use it only to approximate a dollar value; no market-data feed is involved.

Source: SEC fails-to-deliver data (public domain).

Common questions

What are fails-to-deliver (FTD) for BIIB?: A fail-to-deliver happens when a trade in BIIB isn't settled by the delivery date — the seller doesn't hand over the shares on time. The SEC publishes the aggregate number of BIIB shares that failed to deliver on each settlement date. The latest published figure is 104.00 shares (settled 2026-06-03).
Does a high FTD mean BIIB is heavily shorted?: Not directly. Fails-to-deliver is a settlement metric, not short interest — fails arise from mechanical settlement issues, market-making, and long as well as short sellers. A persistent, large fail relative to a name's own history can be worth noting, but FTD alone is not a measure of how shorted a stock is.
How often is BIIB FTD data updated?: The SEC releases fails-to-deliver data twice a month — one file for the first half of each month and one for the second — with a lag. Settlement itself is T+1 (the business day after the trade). Under Regulation SHO, participants must generally close out short-sale fails by the next settlement day (longer windows exist for long sales, bona-fide market making, and certain deemed-to-own securities), and names with large persistent fails can join the exchange threshold-security list after 5 consecutive settlement days. This page rebuilds as new files publish.
Is BIIB's fails-to-deliver a buy or sell signal?: On its own, no — FTD is context, not a verdict. Our current SEC-grounded rating on BIIB is HOLD, based on the company's filings rather than settlement mechanics. Use the fails history as one input alongside the fundamentals.

Full BIIB analysis — verdict, score & filings →Where FTD spikes meet insider & congress signals →

Research and education only — not financial advice. TENKis not a registered investment adviser or broker-dealer and gives no personalized advice. Every call is impersonal — identical for all users, generated on a schedule from SEC filings plus a delayed/third-party price feed — may be wrong or out of date, and is not a recommendation to buy or sell any security. The operator and an affiliated trading operation may hold or trade the securities TENK rates; see Disclosures. Past performance does not guarantee future results. Do your own research.

Fails-to-deliver history

BIIB fails-to-deliver by settlement date, from SEC data
Settlement date	Shares failed	SEC price	Approx. value
2026-06-03	104.00	$188.83	$19.6K
2026-05-27	97.00	$193.08	$18.7K
2026-05-26	6.00	$193.76	$1.16K
2026-05-22	516.00	$189.47	$97.8K
2026-04-30	16.00	$194.38	$3.11K
2026-04-17	122.00	$176.02	$21.5K
2026-04-16	153.00	$180.54	$27.6K

How to read this data

What a fail is. A fail-to-deliver occurs when the seller in a trade doesn’t deliver the shares by the settlement date. The figure here is the aggregate number of shares of BIIB that failed to deliver on each settlement date, as reported by the SEC.
Settlement is T+1. US equities settle one business day after the trade (T+1 since May 2024), so the settlement date shown is one business day after the trade that failed.
The SEC publishes twice a month. Fails data is released in two files per month — the first and second halves — on a lag, so the most recent settlement dates appear only after the next publication.
Reg SHO close-out. Participants must generally close out short-sale fails by the next settlement day after they arise (longer windows apply to long-sale and bona-fide market-making fails, and a 35-calendar-day window only to certain deemed-to-own securities). Names whose fails stay large for 5 consecutive settlement days join the exchange threshold-security list, which brings stricter close-out duties — so persistent large fails are the exception, not the norm.
Not short interest. Fails arise from settlement mechanics and market making as well as short selling, and are not a direct measure of how heavily a stock is shorted. The SEC price column is the prior-day closing price the SEC ships in the same file — we use it only to approximate a dollar value; no market-data feed is involved.

Source: SEC fails-to-deliver data (public domain).

Common questions

What are fails-to-deliver (FTD) for BIIB?: A fail-to-deliver happens when a trade in BIIB isn't settled by the delivery date — the seller doesn't hand over the shares on time. The SEC publishes the aggregate number of BIIB shares that failed to deliver on each settlement date. The latest published figure is 104.00 shares (settled 2026-06-03).
Does a high FTD mean BIIB is heavily shorted?: Not directly. Fails-to-deliver is a settlement metric, not short interest — fails arise from mechanical settlement issues, market-making, and long as well as short sellers. A persistent, large fail relative to a name's own history can be worth noting, but FTD alone is not a measure of how shorted a stock is.
How often is BIIB FTD data updated?: The SEC releases fails-to-deliver data twice a month — one file for the first half of each month and one for the second — with a lag. Settlement itself is T+1 (the business day after the trade). Under Regulation SHO, participants must generally close out short-sale fails by the next settlement day (longer windows exist for long sales, bona-fide market making, and certain deemed-to-own securities), and names with large persistent fails can join the exchange threshold-security list after 5 consecutive settlement days. This page rebuilds as new files publish.
Is BIIB's fails-to-deliver a buy or sell signal?: On its own, no — FTD is context, not a verdict. Our current SEC-grounded rating on BIIB is HOLD, based on the company's filings rather than settlement mechanics. Use the fails history as one input alongside the fundamentals.