XBI · WMTMT

Aug 20Aug 21Aug 24Aug 25Aug 26

30-minute bars · index reconstructed live from member prices

Breadth

89 / 147

stocks fell with the index

Concentration

100%+

of the decline from MRNA, SYRE, ORKA

Biggest driver

MRNA −0.78

MODERNA INC, −14.18%

Biggest offset

PURR +0.21

HYPERLIQUID STRATEGIES, +23.11%

What drove it

147 members · detractors first · 1W · residual 9.9bp within 60bp gate

The XBI fell 0.68% (−1.16 pts) on the week, and more than all of that decline came from just three stocks: MRNA, SYRE, ORKA.

Read the latest market-close note: A Flat Headline on the S&P 500 Masks a Split Between Goldman Sachs and Apple

+2.7 pts from 59 gainers−3.8 pts from 88 losers

net −1.2 pts · losers outweigh gainers 1.4 to 1

Stock

Points

Return

XBIsum of all 147 stocks

−1.2

−0.68%

MRNAMODERNA INC

−0.8

−14.18%

SYRESPYRE THERAPEUTICS INC

−0.3

−14.06%

ORKAORUKA THERAPEUTICS INC

−0.2

−9.34%

RLAYRELAY THERAPEUTICS INC

−0.1

−6.17%

INSMINSMED INC

−0.1

−4.80%

BBIOBRIDGEBIO PHARMA INC

−0.1

−5.46%

BMRNBIOMARIN PHARMACEUTICAL INC

−0.1

−5.37%

VKTXVIKING THERAPEUTICS INC

−0.1

−4.45%

RGNXREGENXBIO INC

−0.1

−21.96%

PCVXVAXCYTE INC

−0.1

−3.49%

PRAXPRAXIS PRECISION MEDICINES I

−0.1

−2.28%

RYTMRHYTHM PHARMACEUTICALS INC

−0.1

−3.34%

MIRMMIRUM PHARMACEUTICALS INC

−0.1

−3.65%

ARQTARCUTIS BIOTHERAPEUTICS INC

−0.1

−4.99%

CGONCG ONCOLOGY INC

−0.1

−2.80%

117 othersclick to expand the full index

−0.7

CDNACAREDX INC

+0.1

+9.57%

ERASERASCA INC

+0.1

+5.98%

QUREUNIQURE NV

+0.1

+4.49%

NTRANATERA INC

+0.1

+3.58%

VIRVIR BIOTECHNOLOGY INC

+0.1

+13.41%

SMMTSUMMIT THERAPEUTICS INC

+0.1

+8.54%

SRRKSCHOLAR ROCK HOLDING CORP

+0.1

+6.25%

IDYAIDEAYA BIOSCIENCES INC

+0.1

+6.97%

BHVNBIOHAVEN LTD

+0.1

+20.01%

TGTXTG THERAPEUTICS INC

+0.1

+6.46%

INBXINHIBRX BIOSCIENCES INC

+0.1

+23.51%

GRALGRAIL INC

+0.1

+7.61%

VERAVERA THERAPEUTICS INC

+0.2

+14.08%

TWSTTWIST BIOSCIENCE CORP

+0.2

+6.34%

PURRHYPERLIQUID STRATEGIES

+0.2

+23.11%

Cap weighting, illustrated

TWIST BIOSCIENCE CORP and MAPLIGHT THERAPEUTICS INC moved almost identically (+6.34% vs +5.84%), yet TWST moved the XBI 19.3× as much. In a cap-weighted index, the bigger company's weight turns the same percentage move into far more points.

Attribution map

slicing the −1.16 pt move · cell size = points contributed · color = direction, intensity = return

MRNA−0.8 pts(−14.2%)

SYRE−0.3 pts

ORKA−0.2 pts(−9.3%)

PURR+0.2 pts(+23.1%)

TWST+0.2 pts(+6.3%)

VERA+0.2 pts(+14.1%)

GRAL+0.1 pts

INBX

TGTX+0.1 pts

BHVN+0.1 pts

RLAY−0.1 pts

INSM−0.1 pts

IDYA

SRRK

BBIO−0.1 pts

BMRN−0.1 pts

SMMT

VKTX−0.1 pts

VIR+0.1 pts

NTRA

QURE

RGNX−0.1 pts

CDNA+0.1 pts

KRYS

PCVX

BEAM

RYTM−0.1 pts

MIRM−0.1 pts

CGON−0.1 pts

REGN

DNLI

NVAX

IONS

PTGX

ADMA

ANNX

VCYT

IMVT

IOVA

ZBIO

MNKD

ROIV

BCRX

ALKS

UTHR

VRDN

XNCR

TSHA

IRON

ALLO

CRVS

IMMX

CLDX

KURA

CTMX

ACAD

SRPT

Concentration curve

cumulative share of the −1.16 pt move · sorted by contribution

When they drove it

cumulative points through the period

Breadth

member returns, this period

−30%−20%−10%0%+10%+20%

From −21.96% (RGNX) to +23.51% (INBX). Equal-weight, the XBI would be −0.09% vs the actual −0.68%; the gap is what cap weighting did.

By sector

point contribution · sums to −1.16 pts

-147

−1.2

The year, session by session

every trading day of 2026 · hover for the move

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SPDR S&P Biotech ETF

What drove it

Attribution map

Concentration curve

When they drove it

Breadth

By sector

The year, session by session

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