MFS Research Fund

S000002438MFS Series Trust VCIK 0000200489

Share classes

9 classes of this one portfolio · 0 exchange-listed

Class ID	Symbol	Status	Security in the master	Type
C000006538	MFRBX	NOT_LISTED	not exchange-listed	—
C000006539	MFRCX	NOT_LISTED	not exchange-listed	—
C000006533	MFRFX	NOT_LISTED	not exchange-listed	—
C000006545	MFRHX	NOT_LISTED	not exchange-listed	—
C000006534	MFRJX	NOT_LISTED	not exchange-listed	—
C000034431	MFRKX	NOT_LISTED	not exchange-listed	—
C000006542	MFRLX	NOT_LISTED	not exchange-listed	—
C000006540	MRFIX	NOT_LISTED	not exchange-listed	—
C000006544	MSRRX	NOT_LISTED	not exchange-listed	—

The share-class bridge is a snapshot, not history. The SEC's fund share-class file says what each class trades as today, not what it traded as at a past report date. A fund that changed ticker or converted from a mutual fund resolves to its present-day symbol for every historical month shown.

Share classes

Report period

1 period filed. Holdings below describe the selected month only.

2026-03-31

Filing

NPORT-P · filed 2026-05-26

Report date: 2026-03-31
Net assets: $7,326,630,101.24
Total assets: $7,329,965,469.63
Total liabilities: $3,335,368.39
Assets invested: $0
Cash not reported in C or D: $0
Amendment: No
Accession: 0002071691-26-011423

By asset category

N-PORT Item C.4.a

ECEquity - common$7.27B99.3%

STIVShort-term investment veh…$51.41M0.7%

DODerivative - other$0.000.0%

By asset category

By issuer category

N-PORT Item C.4.b

CORPCorporate$7.27B99.3%

RFRegistered fund$51.41M0.7%

OTHEROther; the filer describe…$0.000.0%

By issuer category

By investment country

as filed

USUS$6.55B89.5%

IEIE$481.37M6.6%

LULU$79.65M1.1%

CHCH$72.94M1.0%

CACA$67.11M0.9%

JEJE$34.87M0.5%

BMBM$24.08M0.3%

GBGB$11.23M0.2%

By country

Classification look-through

Positions resolved to the master through ISIN, then rolled up through the taxonomy. 96.4% of reported value reaches a classification.

Equity · Information Technology(20)$2.85B39.0%

Equity · Financials(13)$988.95M13.5%

Equity · Health Care(13)$722.40M9.9%

Equity · Consumer Discretionary(11)$684.75M9.3%

Equity · Industrials(14)$665.94M9.1%

Equity · Communication Services(4)$388.17M5.3%

Not resolved to the master(5)$267.15M3.6%

Equity · Consumer Staples(8)$260.07M3.6%

Equity · Utilities(5)$189.18M2.6%

Equity · Energy(5)$139.62M1.9%

Equity · Materials(2)$82.64M1.1%

Equity(1)$62.64M0.9%

Equity · Real Estate(1)$18.19M0.2%

Classification covers part of the master. 5,771 of 13,106 active securities are classified. Anything unclassified is shown as its own band rather than dropped, so a look-through total that falls short of 100% is telling you about coverage, not about the fund.

Percentages are of the reported value of positions above ($7.32B), not of the fund’s net assets ($7.33B). The two differ by cash, derivatives filed with no market value, and rounding.

Classification look-through

Holdings

102 positions in this filing

Issuer nameAsset categoryIssuer categoryCountry

Issuer↕	In master	CUSIP / ISIN	Asset	Balance↕	Value↕	Weight▼	Country
NVIDIA Corp.	NVDA	67066G104 US67066G1040	EC CORP	3,505,420 NS	$611.35M	8.344%

1–50 of 102

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Balance is meaningless without its unit. N-PORT Item C.2.a says what the balance column counts: shares (NS), principal amount (PA), contracts (NC), or something the filer describes (OU). A bond position read as a share count is off by orders of magnitude. Every balance on this page carries its unit code.

Missing CUSIPs are filed as placeholders. Filers with no CUSIP conventionally write 999999999 or N/A rather than leaving the field blank — 1,187,114 of 5,347,869 positions do. Those are shown as missing here, not as identifiers.