MRBBX Mutual Fund

NAV$9.42

AUM$383,383.05

TER1.35%

Holdings1,075

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MRBBX Mutual Fund

NAV$9.42

MFS Total Return Bond Fund Class B

AUM$383,383.05

TER1.35%

Holdings1,075

See how much of MRBBX you already own

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Overview Performance Chart Dividends Top Holdings All Holdings Sectors Geography Similar Compare Overlap

Showing top 50 of 739 holdings · as of Jan 31, 2026

MRBBX holdings, by weight
#	Ticker	Name	Weight	Cumulative	Shares	Mkt value	Sector	Industry
1	Debt	Us Treasury NoteFinancials · Diversified Financial Services	3.85%	3.9%	-	$321.92M	Financials	Diversified Financial Services
2	Debt	Us Treas BdsFinancials · Banks	2.12%	6.0%	-	$177.23M	Financials	Banks
Sector and industry · Pro
3	Debt	United States Treasuryu.S. Treasury Notes	2.04%	8.0%	-	$170.14M
4	Debt	Treasury Bond	1.97%	10.0%	-	$164.89M
5	Debt	Us Treas Nts	1.89%	11.9%	-	$158.23M
6	Debt	United States Govt Us Treasury N/B 08/43 4.375	1.16%	13.0%	-	$96.90M
7	Debt	U.S. Treasury Notes, 4.875%, 10/31/2028	1.12%	14.2%	-	$93.93M
8	—	Freddie Mac Pool 2052-03-01	1.10%	15.3%	-	$91.70M
9	—	Mfs Institutional Money Market Portfolio	1.10%	16.4%	91,559,146	$91.58M
10	Debt	U.S. Treasury Bonds	1.05%	17.4%	-	$87.43M
11	Debt	Treasury Bond (Otr) 4.5% Nov 15, 2054	1.00%	18.4%	-	$83.31M
12	Debt	Us Treas Nts	0.87%	19.3%	-	$72.47M
13	Debt	US Treasury Bonds 1.62% 15-11-2050	0.83%	20.1%	-	$69.47M
14	Debt	Us Treasury Note	0.78%	20.9%	-	$65.05M
15	Debt	Us Treasury N/B 11/35 4	0.73%	21.6%	-	$61.02M
16	Debt	Us Treasury N/B 08/30 3.625	0.68%	22.3%	-	$56.64M
17	Debt	Treasury Note (Otr) 3.38% Dec 31, 2027	0.68%	23.0%	-	$57.03M
18	Debt	U.S. Treasury Bond 1.375%, 11/15/40	0.57%	23.5%	-	$47.93M
19	Debt	Macquarie Group Ltd Mtn 144A 4.44% Jun 21, 2033	0.56%	24.1%	-	$46.43M
20	Debt	Ntt Finan	0.56%	24.7%	-	$46.88M
21	Debt	United States Treasury Note/Bond	0.54%	25.2%	-	$45.50M
22	Debt	Treasury Bond	0.54%	25.7%	-	$45.40M
23	Debt	Us Treas Bds	0.54%	26.3%	-	$45.26M
24	—	Wells Fargo & Co. 2.572% 2031-02-11	0.51%	26.8%	-	$42.49M
25	—	Loancore Issuer Ltd., Series 2021-Cre6, Class B 5.6946708 2038-11-15	0.51%	27.3%	-	$42.88M
26	Debt	Bank Of America Corp	0.50%	27.8%	-	$41.40M
27	—	Arbor Realty Commercial Real Estate Notes 2022-Fl1 Arclo 2022-Fl1 D 8.0666208 01/15/2037	0.48%	28.3%	-	$40.41M
28	—	LoanCore	0.48%	28.8%	-	$39.85M
29	Debt	United States Treasury Note/Bond 2029-04-30	0.47%	29.2%	-	$39.13M
30	Debt	Bank of America Corp	0.45%	29.7%	-	$37.19M
31	Debt	Discover Financial Svs Sr Unsecured 11/32 6.7	0.45%	30.1%	-	$37.70M
32	—	Nrzt_25Nqm4 A1 144A 5.35 Jul 25, 2065	0.45%	30.6%	-	$37.26M
33	—	Umbs Tba 30yr 2% Feb 21to Be Announced 2.00000000	0.45%	31.0%	-	$37.41M
34	Debt	Bxmt Ltd	0.45%	31.5%	-	$37.70M
35	Debt	Cheniere Energy Partners Lp	0.42%	31.9%	-	$35.40M
36	SMFG	Sumitomo Mitsui Financial Group In 2.13 Jul 08, 2030	0.41%	32.3%	-	$34.63M
37	—	Iron Mountain Inc 144a 4.5% Feb 15, 2031	0.41%	32.7%	-	$34.35M
38	—	Black Diamond Clo Ltd., Series 2021-1A, Class A2R 5.5191996 2034-11-22	0.41%	33.1%	-	$34.07M
39	—	Us Penske Automotive 3 3/4% Due 29	0.40%	33.5%	-	$33.39M
40	PAA	Plains All American Pipeline Limited Partnership/Plains All American Pipeline Finance Corporation (USD) Callable 3.550% Dec 15, 2029	0.39%	33.9%	-	$32.33M
41	Debt	Transdigm Inc	0.39%	34.3%	-	$32.93M
42	—	Ubs Commercial Mortgage Trust, Series 2017-C7, Class A4	0.39%	34.7%	-	$32.71M
43	—	American Credit Acceptance Rec	0.38%	35.1%	-	$31.94M
44	—	Enel Finance International Nv	0.36%	35.4%	-	$29.91M
45	—	Quikrete Holdi 6.375 3/32	0.36%	35.8%	-	$29.80M
46	Debt	Us Treasury N/ 4.75 11/53	0.36%	36.2%	-	$30.09M
47	Debt	Sammons Financial Group Sr Unsecured 144A 04/34 6.875	0.35%	36.5%	-	$29.04M
48	Debt	Mitsubishi Ufj Fin Grp	0.34%	36.8%	-	$28.41M
49	E	Eni Spa	0.34%	37.2%	-	$28.05M
50	Debt	JPMorgan Chase Co Callable Notes Variable	0.34%	37.5%	-	$28.10M
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Not reported for this fund: share changes.

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MRBBX Mutual Fund All Holdings

MRBBX holdings total 1075 positions. The top 10 holdings account for 17.4% of the fund, led by Us Treasury Note 4.125% Feb 15 27 at 3.9%, Us Treas Bds 4.75% 11/15/43 at 2.1%, United States Treasuryu.S. Treasury Notes at 2.0%.

MRBBX portfolio concentration is well-diversified, with the top 10 representing 17.4% of total assets. The largest sector exposure is Financials at 48.6%.

MRBBX sectors provide a detailed breakdown. MRBBX overlap shows how holdings compare to other funds in your portfolio.