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Proto Labs Inc

PRLB
Exchange
NYSE
Industry
Fabricated Structural Metal Products
SEC CIK
0001443669

In the last 90 days, Proto Labs Inc insiders filed 2 open-market purchases and 2 sales; 280 institutions reported holding it in 13F filings for Q2 2026, worth $1.83B in total; ARK Invest is the only superinvestor holding it.

Four kinds of short-selling data, each measuring something different:

  • Short interest: shares sold short and not yet bought back, as of a settlement date. FINRA publishes it twice a month, about eight business days after the settlement date.
  • Daily short volume: shares sold short each day in off-exchange trades reported to FINRA. It counts trades, not open positions, and is published the next day.
  • Fails-to-deliver: shares not delivered by the settlement date. The SEC publishes them twice a month, about two weeks late.
  • ATS (dark pool) volume: weekly volume on alternative trading systems and other off-exchange venues. FINRA publishes it two to four weeks after the week.

More in the glossary.

Short interest

Shares sold short and not yet bought back, from FINRA, on every settlement date in the last two years.

Short interest
616.3K
Shares, settlement Oct 30, 2026
Change
−36.9K
−5.7% vs. Oct 15, 2026
Days to cover
2.41
Short interest ÷ average daily volume
Average daily volume
255.7K
Shares, as reported by FINRA
Short interest by settlement date
Oct 31, 2024: 1,014,032 sharesNov 15, 2024: 711,044 sharesNov 29, 2024: 781,452 sharesDec 13, 2024: 892,811 sharesDec 31, 2024: 682,114 sharesJan 15, 2025: 669,885 sharesJan 31, 2025: 594,935 sharesFeb 14, 2025: 675,986 sharesFeb 28, 2025: 755,413 sharesMar 14, 2025: 705,112 sharesMar 31, 2025: 805,840 sharesApr 15, 2025: 890,783 sharesApr 30, 2025: 825,600 sharesMay 15, 2025: 840,509 sharesMay 30, 2025: 820,580 sharesJun 13, 2025: 778,584 sharesJun 30, 2025: 760,144 sharesJul 15, 2025: 656,829 sharesJul 31, 2025: 637,698 sharesAug 15, 2025: 667,965 sharesAug 29, 2025: 680,732 sharesSep 15, 2025: 688,674 sharesSep 30, 2025: 631,522 sharesOct 15, 2025: 593,032 sharesOct 31, 2025: 609,446 sharesNov 14, 2025: 703,045 sharesNov 28, 2025: 601,534 sharesDec 15, 2025: 542,670 sharesDec 31, 2025: 461,538 sharesJan 15, 2026: 456,341 sharesJan 30, 2026: 515,791 sharesFeb 13, 2026: 535,467 sharesFeb 27, 2026: 540,900 sharesMar 13, 2026: 586,703 sharesMar 31, 2026: 630,613 sharesApr 15, 2026: 647,664 sharesApr 30, 2026: 612,973 sharesMay 15, 2026: 643,691 sharesMay 29, 2026: 644,067 sharesJun 15, 2026: 700,174 sharesJun 30, 2026: 679,916 sharesJul 15, 2026: 676,418 sharesJul 31, 2026: 675,490 sharesAug 14, 2026: 656,363 sharesAug 31, 2026: 615,345 sharesSep 15, 2026: 753,948 sharesSep 30, 2026: 739,819 sharesOct 15, 2026: 653,218 sharesOct 30, 2026: 616,285 shares
Short interest in PRLB by settlement date
Settlement dateShort interestChangeChange %Avg. daily volumeDays to cover
Oct 30, 2026616.3K−36.9K−5.7%255.7K2.41
Oct 15, 2026653.2K−86.6K−11.7%206.2K3.17
Sep 30, 2026739.8K−14.1K−1.9%300.8K2.46
Sep 15, 2026753.9K+138.6K+22.5%156.4K4.82
Aug 31, 2026615.3K−41.0K−6.3%174.9K3.52
Aug 14, 2026656.4K−19.1K−2.8%219.2K2.99
Jul 31, 2026675.5K−928−0.1%164.3K4.11
Jul 15, 2026676.4K−3.50K−0.5%245.2K2.76
Jun 30, 2026679.9K−20.3K−2.9%307.3K2.21
Jun 15, 2026700.2K+56.1K+8.7%210.1K3.33
May 29, 2026644.1K+376+0.1%192.7K3.34
May 15, 2026643.7K+30.7K+5.0%223.3K2.88
Apr 30, 2026613.0K−34.7K−5.4%136.6K4.49
Apr 15, 2026647.7K+17.1K+2.7%145.3K4.46
Mar 31, 2026630.6K+43.9K+7.5%165.0K3.82
Mar 13, 2026586.7K+45.8K+8.5%170.4K3.44
Feb 27, 2026540.9K+5.43K+1.0%174.3K3.10
Feb 13, 2026535.5K+19.7K+3.8%303.7K1.76
Jan 30, 2026515.8K+59.5K+13.0%174.6K2.95
Jan 15, 2026456.3K−5.20K−1.1%131.6K3.47
Dec 31, 2025461.5K−81.1K−15.0%164.7K2.80
Dec 15, 2025542.7K−58.9K−9.8%116.8K4.65
Nov 28, 2025601.5K−101.5K−14.4%161.3K3.73
Nov 14, 2025703.0K+93.6K+15.4%252.4K2.79
Oct 31, 2025609.4K+16.4K+2.8%240.4K2.54
Oct 15, 2025593.0K−38.5K−6.1%174.6K3.40
Sep 30, 2025631.5K−57.2K−8.3%200.0K3.16
Sep 15, 2025688.7K+7.94K+1.2%142.6K4.83
Aug 29, 2025680.7K+12.8K+1.9%168.9K4.03
Aug 15, 2025668.0K+30.3K+4.8%216.1K3.09
Jul 31, 2025637.7K−19.1K−2.9%195.2K3.27
Jul 15, 2025656.8K−103.3K−13.6%144.0K4.56
Jun 30, 2025760.1K−18.4K−2.4%203.6K3.73
Jun 13, 2025778.6K−42.0K−5.1%260.0K2.99
May 30, 2025820.6K−19.9K−2.4%181.5K4.52
May 15, 2025840.5K+14.9K+1.8%181.1K4.64
Apr 30, 2025825.6K−65.2K−7.3%279.0K2.96
Apr 15, 2025890.8K+84.9K+10.5%212.5K4.19
Mar 31, 2025805.8K+100.7K+14.3%182.1K4.43
Mar 14, 2025705.1K−50.3K−6.7%193.1K3.65
Feb 28, 2025755.4K+79.4K+11.8%246.5K3.06
Feb 14, 2025676.0K+81.1K+13.6%353.6K1.91
Jan 31, 2025594.9K−75.0K−11.2%224.1K2.65
Jan 15, 2025669.9K−12.2K−1.8%155.4K4.31
Dec 31, 2024682.1K−210.7K−23.6%349.5K1.95
Dec 13, 2024892.8K+111.4K+14.3%219.9K4.06
Nov 29, 2024781.5K+70.4K+9.9%262.0K2.98
Nov 15, 2024711.0K−303.0K−29.9%493.2K1.44
Oct 31, 20241.01M+40.6K+4.2%162.1K6.26

Fails-to-deliver

Shares that weren't delivered by the settlement date, from the SEC, for the last 30 dates with fails. The price is the previous day's closing price published by the SEC.

Fails-to-deliver in PRLB by settlement date
Settlement dateSharesPriceValue
Sep 16, 202650$79.09$3.95K
Jul 20, 20261,000$77.62$77.6K
Jul 17, 20269$77.36$696.24
Jul 7, 202640$77.14$3.09K
Jun 18, 202617$79.57$1.35K
Jun 15, 2026386$78.94$30.5K
Jun 11, 20262,721$73.78$200.8K
May 18, 202668$72.01$4.90K
May 13, 20262,877$71.02$204.3K
May 1, 20262,695$64.81$174.7K
Apr 16, 2026113$63.24$7.15K
Mar 31, 202650$55.38$2.77K
Mar 23, 20269$55.75$501.75
Mar 20, 202610$56.65$566.5
Mar 10, 20263,534$57.59$203.5K
Mar 5, 20261,686$63.13$106.4K
Mar 4, 20265,257$61.96$325.7K
Mar 2, 2026491$62.08$30.5K
Feb 25, 20263,094$63.28$195.8K
Feb 23, 2026682$65.37$44.6K
Feb 17, 2026132$67.52$8.91K
Jan 28, 202610$52.48$524.8
Jan 9, 2026239$54.93$13.1K
Jan 5, 20263$51.35$154.05
Dec 22, 202551$52.12$2.66K
Dec 2, 202523$50.03$1.15K
Oct 16, 2025157$55.22$8.67K
Oct 14, 20251,965$51.04$100.3K
Oct 2, 202516$49.00$784
Sep 29, 20256$50.40$302.4

Daily short volume

Off-exchange short-sale volume, not short interest: shares sold short each day in trades reported to FINRA, for the last 30 trading days.

The short volume ratio isn't a sentiment gauge: market makers sell short to fill buy orders and to hedge, so short sales are usually about half of off-exchange volume.

Off-exchange short volume in PRLB by trade date
Trade dateShort volumeShort exemptOff-exchange volumeShort volume ratio
Nov 10, 202635,117066,91152.5%
Nov 9, 202655,79225105,67452.8%
Nov 6, 202653,8690103,92851.8%
Nov 5, 202676,779100159,58748.1%
Nov 4, 202645,2380101,87044.4%
Nov 3, 202670,4760141,95649.6%
Nov 2, 2026106,9293,038163,39465.4%
Oct 30, 2026124,3893,215232,41453.5%
Oct 29, 2026116,2053,094214,80354.1%
Oct 28, 202670,519088,15680.0%
Oct 27, 202641,176058,96969.8%
Oct 26, 202632,725056,03058.4%
Oct 23, 202633,95014053,67163.3%
Oct 22, 202639,54410069,79856.7%
Oct 21, 202644,551059,54274.8%
Oct 20, 202643,491067,81764.1%
Oct 19, 202633,777052,24764.6%
Oct 16, 202641,793075,94655.0%
Oct 15, 202654,265088,32861.4%
Oct 14, 202637,249059,98862.1%
Oct 13, 202621,576133,46564.5%
Oct 12, 202623,048047,71748.3%
Oct 9, 202636,640056,50564.8%
Oct 8, 202627,505046,59759.0%
Oct 7, 202632,210062,42351.6%
Oct 6, 202649,7670126,09239.5%
Oct 5, 202662,852080,23978.3%
Oct 2, 202660,566092,40565.5%
Oct 1, 202633,923076,16244.5%
Sep 30, 202636,593054,52367.1%

ATS (dark pool) volume

Weekly volume on alternative trading systems (ATS) and other off-exchange (OTC) venues, from FINRA, for the last 12 weeks. ATS share is ATS volume ÷ (ATS + OTC volume), not a share of all trading.

Weekly ATS and OTC volume in PRLB
Week ofTierATS sharesATS tradesOther OTC sharesOther OTC tradesATS share
Oct 5, 2026T2234,6089,652215,5824,20052.1%
Sep 28, 2026T2271,75314,007251,9953,88551.9%
Sep 21, 2026T2314,74712,475268,5525,08254.0%
Sep 14, 2026T2257,20612,030422,7144,51837.8%
Sep 7, 2026T2108,3678,46364,0112,10562.9%
Aug 31, 2026T2155,0899,355102,1973,11560.3%
Aug 24, 2026T2181,3038,931130,6364,16258.1%
Aug 17, 2026T2208,67612,466131,1254,11261.4%
Aug 10, 2026T2176,92011,12194,7713,55565.1%
Aug 3, 2026T2317,34715,993182,8515,62063.4%
Jul 27, 2026T2226,3689,591137,7932,88462.2%
Jul 20, 2026T2145,4729,48966,7722,25068.5%