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Shannon River Fund Management LLC · Q2 2026 13F · SEC CIK 1301050

Spencer Waxman portfolio

Hedge fundShannon River Fund Management 13F holdings. Filed 2026-08-13 for Q2 2026. Open the filing ↗ · All SEC filings ↗

Reported 13F value
$1.1B
Reported positions
37
Top holdings a year, 3 yrs
+42.7%
Assets under management
$904.7M

Spencer Waxman is the founder of Shannon River Fund Management, which reported 37 positions worth $1.1B in its Q2 2026 13F, filed 2026-08-13. Its largest holdings were Tower Semiconductor Ltd (TSEM, 8.9%), Flex Ltd Ord (FLEX, 5.5%), Advanced Micro Devices Inc (AMD, 5.5%). A portfolio copying its top holdings returned 42.7% a year over the last 3 years, against 20.4% for the S&P 500.

Spencer Waxman holdings all 37 positions.

Weights are shares of the filer's total reported 13F value, compared with Q1 2026. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.

Spencer Waxman 13F holdings
Stock% of 13F valueShare changeReported value
TSEMTower Semiconductor Ltd8.9%-24.1%$99.8M
FLEXFlex Ltd Ord5.5%+22.0%$61.6M
AMDAdvanced Micro Devices Inc5.5%—$61.4M
IDCCInterdigital Inc4.7%+240.8%$52.2M
CLSCelestica Inc4.6%+161.6%$51.1M
COHRCoherent Corp4.6%+47.1%$51.0M
HNGEHinge Health, Inc.4.2%+34.5%$46.6M
EXTRExtreme Networks Inc4.1%+8.5%$46.1M
KLICKulicke & Soffa Industries Inc4.0%—$44.8M
TWLOTwilio Inc3.7%—$41.5M
CIENCiena Corp3.6%—$39.9M
LYVLive Nation Entertainment in3.5%-26.6%$39.6M
RMBSRambus Inc Del3.5%-12.6%$38.7M
QNTQuantinuum Inc3.4%—$38.4M
UTIUniversal Technical Inst Inc3.4%—$38.1M
ABNBAirbnb Inc3.2%+0.3%$35.5M
TTWOTake-Two Interactive Softwar3.1%—$34.5M
OUSTOuster Inc2.5%—$28.1M
PDFSPDF Solutions Inc2.3%—$26.2M
NOKNokia Corp2.3%—$25.3M
ALNTAllient Inc2.0%—$22.7M
RKLBRocket Lab Corp2.0%—$22.5M
FFIVF5 Inc1.9%+2.1%$21.3M
DYDycom Inds Inc1.8%—$20.0M
CIFRCipher Digital Inc1.5%—$16.4M
LIONLionsgate Studios Corp1.4%+0.9%$16.1M
DLRDigital Rlty Tr Inc1.4%+197.5%$15.9M
GWREGuidewire Software Inc1.2%+80.1%$13.9M
SPHRSphere Entertainment Co1.1%+0.7%$12.8M
GLBEGlobal E Online Ltd1.1%—$12.3M
AMPXAmprius Technologies Inc1.0%—$11.6M
APLDApplied Digital Corp0.9%—$9.9M
NETCloudflare Inc0.5%—$5.8M
AMKRAmkor Technology Inc0.5%—$5.7M
MUMicron Technology Inc0.5%—$5.2M
BWBabcock & Wilcox Enterprises0.4%—$4.7M
MXLMaxlinear Inc0.3%—$3.5M

What Spencer Waxman bought and sold in Q2 2026, against Q1 2026.

New positions

Added to

Reduced

Sold out

Share counts compared with the Q1 2026 13F; a split also changes share counts.

How the holdings did against the S&P 500.

1 year
+67.0% /yr
S&P 500 +20.1%
3 years
+42.7% /yr
S&P 500 +20.4%
5 years
+20.6% /yr
S&P 500 +11.6%

A portfolio of the filer's 20 largest 13F positions, weighted by value, bought the trading day after each 13F was filed and held until the next one was: what copying this filer could have earned. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.

Reported 13F value by quarter.

13F value by quarter
Quarter13F valuePositions
Q2 2026$1.1B37
Q1 2026$524.1M28
Q4 2025$637.5M26
Q3 2025$621.2M20
Q2 2025$649.3M22
Q1 2025$383.2M14
Q4 2024$565.7M17
Q3 2024$661.7M18
Q2 2024$581.4M21
Q1 2024$449.1M18
Q4 2023$361.4M17
Q3 2023$340.1M15

Questions about Spencer Waxman's portfolio

Who is Spencer Waxman?

Spencer Waxman is the founder of Shannon River Fund Management, a hedge fund that files its US stock holdings with the SEC on Form 13F under the name Shannon River Fund Management LLC.

What stocks does Spencer Waxman own?

Shannon River Fund Management LLC's latest 13F, for Q2 2026 and filed Aug 13, 2026, lists 37 positions worth $1.1B. The largest are Tower Semiconductor Ltd (TSEM) at 8.9%, Flex Ltd Ord (FLEX) at 5.5%, Advanced Micro Devices Inc (AMD) at 5.5%, Interdigital Inc (IDCC) at 4.7% and Celestica Inc (CLS) at 4.6%.

What did Spencer Waxman buy last quarter?

In Q2 2026, Shannon River Fund Management LLC added a new position in Advanced Micro Devices Inc (AMD), a new position in Kulicke & Soffa Industries Inc (KLIC), a new position in Twilio Inc (TWLO), a new position in Ciena Corp (CIEN), a new position in Quantinuum Inc (QNT), Interdigital Inc (IDCC) (+240.8% shares), Digital Rlty Tr Inc (DLR) (+197.5% shares) and Celestica Inc (CLS) (+161.6% shares), compared with its Q1 2026 filing.

What did Spencer Waxman sell last quarter?

In Q2 2026, Shannon River Fund Management LLC sold all of Marvell Technology Inc (MRVL), sold all of Axon Enterprise Inc (AXON), sold all of Toast Inc (TOST), sold all of Legence Corp (LGN), sold all of Adtran Holdings Inc (ADTN), Live Nation Entertainment in (LYV) (-26.6% shares), Tower Semiconductor Ltd (TSEM) (-24.1% shares) and Rambus Inc Del (RMBS) (-12.6% shares), compared with its Q1 2026 filing.

How has Spencer Waxman's portfolio performed?

A portfolio copying Shannon River Fund Management LLC's 20 largest 13F holdings each quarter, from the day each filing was public, returned +42.7% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: +67.0% against +20.1%. Over 5 years: +20.6% a year against +11.6%.

When is Shannon River Fund Management LLC's next 13F filing due?

13F filings are due 45 days after each quarter ends. Shannon River Fund Management LLC's filing for the quarter ending Sep 30, 2026 is due by Nov 14, 2026; this page updates the day after it is published.

How much money does Shannon River Fund Management LLC manage?

Shannon River Fund Management LLC reported $904.7M of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $1.1B.