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Funds (13F)

Westfield Capital Management Co LP

Backtest from 16 Aug 2013 to 2 Nov 2026 · weekly · hypothetical

Watch this strategy
Return a year
+14.2%
S&P 500 +14.1%
Last 12 months
+6.5%
S&P 500 +12.1%
Sharpe ratio
0.68
S&P 500 0.78
Biggest drop
−34.6%
S&P 500 −31.8%
$10.0k$20.0k$40.0k 2013201520172019202120232025 $57.4k$57.0k
StrategyS&P 500 $10,000 in Westfield Capital Management Co LP from 16 Aug 2013 against the S&P 500 (total return) over the same dates, marked weekly, log scale. Hypothetical: before taxes and trading costs.

About

Copies Westfield Capital Management Co LP's quarterly 13F holdings in the companies we cover, weighted by reported value: it buys on the first trading day after each 13F is filed (up to 45 days after the quarter) and holds until the next filing. A 13F shows long US-listed positions only, at the quarter's end, so this misses shorts, cash, bonds, non-US holdings and trading within the quarter.

Westfield Capital Management Co LP's 13F holdings →

Key statistics

MeasureStrategyS&P 500
Return a year (compound)+14.2%+14.1%
Total return+474%+470%
Last 12 months+6.5%+12.1%
Last 3 months−4.4%—
Last month−5.9%—
This year so far+6.3%—
Volatility a year19.2%16.0%
Sharpe ratio0.680.78
Biggest drop−34.6%−31.8%
Beta to the S&P 5001.151.00
Alpha a year (t-statistic)−1.2% (−0.78)—
Share of weeks up61%—

Sharpe ratio uses returns above the 3-month Treasury bill rate. Alpha is the yearly return left after allowing for the strategy's exposure to the S&P 500 (CAPM); a t-statistic below about 2 means it cannot be told apart from luck.

Insights

CompanyWeightHeld sinceReturn since
NVDA5.3%——
GOOGL4.4%——
ASND4.2%——
AXON2.8%——
FTAI2.6%——
AAPL2.5%——
FIX2.3%——
AVGO1.9%——
MSFT1.7%——
HWM1.7%——
LLY1.6%——
SNOW1.4%——
MKSI1.4%——
META1.3%——
VRT1.2%——
GEV0.9%——
MU0.9%——
V0.9%——
APG0.9%——
TPR0.8%——
RYTM0.8%——
LTH0.8%——
TSM0.8%——
GH0.8%——
PWR0.8%——
NOW0.8%——
AMD0.8%——
PANW0.7%——
WWD0.7%——
ANET0.7%——
LPLA0.7%——
RKLB0.7%——
AS0.7%——
NET0.7%——
AMZN0.7%——
GRMN0.7%——
RRX0.7%——
NTRA0.7%——
MS0.7%——
CRS0.6%——
IOT0.6%——
DT0.6%——
CAT0.6%——
SMTC0.6%——
AME0.6%——
ABVX0.6%——
INSM0.6%——
ITT0.5%——
GILD0.5%——
PTCT0.5%——
BROS0.5%——
CELH0.5%——
MTZ0.5%——
SN0.5%——
CSX0.5%——
FCFS0.5%——
KEY0.5%——
MCHP0.5%——
AMAT0.5%——
MAR0.5%——
PCVX0.5%——
GL0.5%——
FTI0.5%——
XPO0.4%——
LEGN0.4%——
P0.4%——
LRCX0.4%——
JLL0.4%——
ALAB0.4%——
ROK0.4%——
IEX0.4%——
COHR0.4%——
LGN0.4%——
LECO0.4%——
ASML0.4%——
PL0.4%——
ONTO0.4%——
COR0.4%——
RVMD0.4%——
SNDK0.4%——
AFRM0.4%——
LYV0.4%——
NPO0.4%——
PR0.3%——
ARES0.3%——
IMAX0.3%——
GWRE0.3%——
NXT0.3%——
FROG0.3%——
SNPS0.3%——
ROKU0.3%——
PLXS0.3%——
AIT0.3%——
MSCI0.3%——
HOOD0.3%——
ROST0.3%——
ADPT0.3%——
XENE0.3%——
ORLY0.3%——
C0.3%——
PKG0.3%——
BIRK0.3%——
PLMR0.3%——
EWBC0.3%——
RRR0.3%——
WTFC0.3%——
CLH0.3%——
CWST0.3%——
TTMI0.3%——
TRGP0.3%——
FPS0.3%——
ALNY0.3%——
COCO0.3%——
RBRK0.3%——
AZO0.3%——
DASH0.2%——
WYNN0.2%——
IDXX0.2%——
SFM0.2%——
PRAX0.2%——
CRM0.2%——
PRIM0.2%——
DY0.2%——
STEP0.2%——
JBHT0.2%——
VST0.2%——
GKOS0.2%——
MTSI0.2%——
TER0.2%——
SAIA0.2%——
NXPI0.2%——
ST0.2%——
HQY0.2%——
BTSG0.2%——
RLAY0.2%——
HLI0.2%——
ENTG0.2%——
CORZ0.2%——
RDNT0.2%——
ORKA0.2%——
CRDO0.2%——
BLDR0.2%——
LSCC0.2%——
DSGX0.2%——
AVNT0.2%——
BRZE0.2%——
FN0.2%——
LNG0.2%——
PODD0.2%——
RBLX0.2%——

Weighted by reported value in the latest 13F, held until the next filing.

PeriodReturn a yearS&P 500SharpeS&P 500Biggest dropBetaAlpha (t)
Whole backtest16 Aug 2013 to 2 Nov 2026+14.2%+14.1%0.680.78−34.6%1.15−1.2% (−0.78)
2018 onwards5 Jan 2018 to 2 Nov 2026+13.2%+13.9%0.550.66−34.6%1.15−1.7% (−0.83)
Last three years3 Nov 2023 to 2 Nov 2026+18.3%+21.8%0.751.16−25.5%1.27−6.4% (−1.73)
Last year7 Nov 2025 to 2 Nov 2026+9.7%+14.2%0.390.84−11.3%1.30−6.2% (−0.81)
DateCompanyAction
14 Aug 2026WULFBought
14 Aug 2026WSMBought
14 Aug 2026WINGBought
14 Aug 2026VRSNBought
14 Aug 2026VIRTBought
14 Aug 2026TTMIBought
14 Aug 2026THBought
14 Aug 2026TERBought
14 Aug 2026SYNABought
14 Aug 2026STXBought
14 Aug 2026STBought
14 Aug 2026SPOTBought
14 Aug 2026SOPHBought
14 Aug 2026SNDKBought
14 Aug 2026SIMOBought
14 Aug 2026SFMBought
14 Aug 2026RNGBought
14 Aug 2026RLAYBought
14 Aug 2026RHPBought
14 Aug 2026RBRKBought
14 Aug 2026RBLXBought
14 Aug 2026QNTBought
14 Aug 2026QBTSBought
14 Aug 2026PTCTBought
14 Aug 2026PIBought

Dated at the rebalance that made the change.

DateCompanyAction
14 Aug 2026ZSSold
14 Aug 2026WGSSold
14 Aug 2026WFCSold
14 Aug 2026TECHSold
14 Aug 2026TDGSold
14 Aug 2026SRRKSold
14 Aug 2026RJFSold
14 Aug 2026PLTRSold
14 Aug 2026PEPSold
14 Aug 2026OPCHSold
14 Aug 2026MTBSold
14 Aug 2026MNDYSold
14 Aug 2026MDTSold
14 Aug 2026MCOSold
14 Aug 2026MCDSold
14 Aug 2026LOWSold
14 Aug 2026KTOSSold
14 Aug 2026KKRSold
14 Aug 2026ITSold
14 Aug 2026IONQSold
14 Aug 2026IMVTSold
14 Aug 2026IBPSold
14 Aug 2026IBMSold
14 Aug 2026HUBSSold
14 Aug 2026HLNESold

Dated at the rebalance that made the change.

Backtests are hypothetical and use today's listed companies only, which flatters results. Past performance does not predict future returns. This is research, not investment advice. How we backtest