The I-bond semiannual variable inflation rate, based on the Sept vs. Mar CPI-U, will be 3.56% starting Nov 1st, for a composite rate of 7.12% (for 6 months) even if the fixed rate (not announced until Monday, Nov 1st) remains 0%, as seems likely.
If an I-bond is purchased before Nov 1st, because interest is compounded semiannually, one would get (1+1.77%)*(1+3.56%) = 5.39% for that bond's first year.

A lot depends I think on how fast rates rise and how much. A gradual increase probably won't hurt bonds much. A rapid increase would. In a scenario where 10-year corporates yield 3% and new issues suddenly yield 6% because of an inflation or default panic, existing bonds yielding 3% would I believe crash hard. But if corporate bond rates gradually increased over a period of years to 6%, the bond market would have more time to adjust to the shift via the income it is already paying to counteract bond price declines and the gradual increase of higher yielding issues in the outstanding bond mix.

The State of MI retired teachers healthcare premiums have actually declined over the last couple of years, but the deductibles and out-of-pocket costs have risen, very substantially. Items like urgent care or ER visits are very costly now, and the drug prices we pay at the pharmacy have risen plenty. It’s much harder to get approval for prescriptions as the insurers constantly force the doctors to rejustify use of a drug the patient has been taking for years. My doctor says his staff spends hours a week talking to retired docs hired by the insurance companies to just say “no” whenever a prescription renewal is presented.
Our Part D provider sends us countless ads urging us to use mail order for refills. One had best read the fine print because there is a $40 minimum charge, even if the Rx is for a month’s supply of Lisinipril, a drug we pay $1.75 for when we buy it at the local pharmacy. If the doctor orders a 90-day supply of the same drug, the pharmacy is required by the insurer to charge us $16. We go in every month because we have always been thrifty.

(This is a 403b, so hey, I wonder if you can sue TIAA for not automatically moving the RMD each year into some nonretirement cash account ... assuming they did not.)
Assuming the relative tried to sue, "failure to mitigate" comes to mind. (Not advice, just a random thought.)
As the IRS notes, "Although the IRA custodian or retirement plan administrator may calculate the RMD, the IRA or retirement plan account owner is ultimately responsible for calculating the amount of the RMD."
https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-required-minimum-distributions#6
Everything in SP500 ETF, I am told.
An S&P 500 ETF investment would have grown at roughly the same rate in a taxable account (since it's extremely tax efficient). So the growth hardly softens the blow, especially since the heirs would have gotten that growth tax-free (up to the estate tax exemption limit, currently about $11.7M). But by leaving the money in the TSA, irrespective of penalties, the growth became taxable as ordinary income.
The calculus would be different had that money been invested in something spinning off tons of ordinary income.

@Crash

I just read that Medicare will eat the increase

Where did you read such a report? Someone doesn't know how to do simple math or what they're writing about!
NOTE: relative to Medicare premium only, not any other changes to Medicare for 2022.
An example: 2021 SS monthly benefit = $2,000/month. The 2022 benefit will be $2,118 ($2,000 X 5.9%). The normal monthly Medicare premium will increase in 2022 from $148.50 to $158.50/month. 2022 SS/monthly benefit increase of $118 - $10, 2022 Medicare monthly premium increase = a net monthly SS benefit increase of $108. This is $1,296/annual.
Someone is doing too much Maui-Wowie. You need to contact whomever wrote what you read to have a re-do moment.

By law, "[t]he standard Part B premiums are set to cover 25% of projected average per capita Part B program costs for the aged, with federal general revenues accounting for the remaining amount."
https://sgp.fas.org/crs/misc/R40082.pdf
However, for 2021 the law was changed so that the federal government absorbed most of the premium increase.

To ... avoid a large premium increase, Congress in the new budget law added enough money to Medicare so, according to a spokesman for House Speaker Nancy Pelosi, the Part B premium will increase only by an estimated $4 a month.

https://www.aarp.org/politics-society/advocacy/info-2020/congress-medicare-part-b.html
So part of the increase for 2022 would seem to be catching up to what 2021 should have been. Thus only the remainder of the 2022 increase would be due to the projected rise in medical costs between 2021 and 2022.
That may not make you feel any better, but it does help to harmonize the 2022 premium increase (whatever that turns out to be) with the small increase in medical costs over the past year.
While CMS announces original Medicare premiums in November, it has already released average increases for private Medicare insurance:

The average premium for Medicare Advantage plans will be lower in 2022 at $19 per month, compared to $21.22 in 2021, while projected enrollment continues to increase. As previously announced, the average 2022 premium for Part D coverage will be $33 per month, compared to $31.47 in 2021.

https://www.cms.gov/newsroom/press-releases/cms-releases-2022-premiums-and-cost-sharing-information-medicare-advantage-and-prescription-drug

...Medicare will eat it anyhow.

There's a lot of that notion going around. Let's walk through that.
I did this relatively quickly - please check my math. Also see Disclaimer below.
Looking ahead...
If your gross SS is $15,000 annually, a 2022 5.9% COLA increases your gross by $885. If SS is $20,000, an increase of $1,180.
No definitive word yet on the Medicare Part B increase for 2022.
Looking back...
In 2020, Part B increased 6.72% to $144.60 monthly from $135.50. Annually that was a $109 increase.
In 2021, Part B increased 2.70% to $148.50 monthly from $144.60. Annually that was a $47 increase.
So...
IF the past two years are any indication, it is very unlikely, barring an extraneously high Pt B increase for 2022, that anyone grossing $15K-$20K annually will not be in a better net position is 2022.
NOTE: Part D premiums are NOT considered here but would also affect net, if applicable, as would other variables, increase in Pt B penalty, etc.
Disclaimer: Data provided by long-since retired auditor type whose calculation accuracy rate may or may not resemble his stellar rate from back in the day. Just sayin'.

...And yet, I just read that Medicare will eat the increase. Should have remembered.

There's a lot of that notion going around. Let's walk through that.
I did this relatively quickly - please check my math. Also see Disclaimer below.
Looking ahead...
If your gross SS is $15,000 annually, a 2022 5.9% COLA increases your gross by $885. If SS is $20,000, an increase of $1,180.
No definitive word yet on the Medicare Part B increase for 2022.
Looking back...
In 2020, Part B increased 6.72% to $144.60 monthly from $135.50. Annually that was a $109 increase.
In 2021, Part B increased 2.70% to $148.50 monthly from $144.60. Annually that was a $47 increase.
So...
IF the past two years are any indication, it is very unlikely, barring an extraneously high Pt B increase for 2022, that anyone grossing $15K-$20K annually will not be in a better net position is 2022.
NOTE: Part D premiums are NOT considered here but would also affect net, if applicable, as would other variables, increase in Pt B penalty, etc.
Disclaimer: Data provided by long-since retired auditor type whose calculation accuracy rate may or may not resemble his stellar rate from back in the day. Just sayin'.

I’ve looked at their site. Your list is accurate as far as it goes. But it appears Price lists fixed income holdings along with stocks in its publishec “portfolio” - with the following important exception:
“Numbers may not add up to 100% exactly due to rounding and/or the exclusion of reserves and other assets. Excludes cash and derivatives.”
So, the remaining 24.32% (not listed as part of the portfolio) likely resides in cash + derivatives.
One way to check this is to call up the complete list of portfolio holdings using another TRP link: Scrolling down to Amazon, one of their larger equity holdings, reveals that it’s listed right along with a number of bond holdings inside that “portfolio.”
https://individual.troweprice.com/staticFiles/gcFiles/pdf/phcafq2.pdf
There’s also language (somewhere in all that) to the effect that fund holdings will be publicly available 30 days after the end of a quarter. That’s seemingly at odds with the 9/30/21 date Roy accurately cited. I’m inclined to think that 9/30/21 date is meant to reflect the latest publicly available accounting. Could be wrong on that. In any case, it isn’t germane to the larger issue explained above.

there’s a fee wavier which appears to drop the ER down to 0.29%
As strange as this may sound, you're reading it backward. The gross ER is 0.29%, while the net ER, after accounting for fee waivers is higher, at 0.31%.
This is because the waiver currently in effect says that the ER will be no higher than 0.31% including a clawback of previously waived expenses.
If the current ER without waivers were, say, 0.35%, then 0.04% would be waived and the ER would be 0.31%. But the current ER without waivers is 0.29%. The fund management is thus allowed to take another 0.02% to get back fees it previously forwent.
The clawback is limited to 0.02% because according to the fee waiver agreement, the net ER cannot rise above 0.31%.
As the prospectus states: "Fees waived and expenses paid under this agreement (and a previous limitation of 0.35%) are subject to reimbursement to T. Rowe Price Associates, Inc., by the fund whenever the class’ expense ratio is below 0.31%."

+1

Just checked TRP’s funds page
“30 Day Yield - Annualized Dividend” for TRBUX is given as 0.69% (not that I pretend to understand all the jargon). Interestingly, there’s a fee wavier which appears to drop the ER down to 0.29%. The ER on TBUX (the etf ) appears to be 0.17%. Seems to boil down to choice of either a 0.69% or 0.81% annualized yield (based on a 0.12% difference in ER).
T. Rowe Price / LINK
-
Fido’s “deferred” ntf fees being what they are does complicate matters. Can’t just buy TRBUX one day and than switch to TBUX the next. I certainly understand @carew388’s frustration.

If I'm interpreting portfolio data correctly from the TRP website dated 9/30/21, PRWCX equity allocation has increased to 75.68%.
Sector Allocation
As a percentage of Total Net Assets
As of 9/30/2021
INFORMATION TECHNOLOGY
14.33%
HEALTH CARE
13.58%
CONSUMER DISCRETIONARY
10.58%
FINANCIALS
10.28%
UTILITIES
7.19%
INDUSTRIALS & BUSINESS SERVICES
7.04%
COMMUNICATION SERVICES
5.97%
OPTION
4.48%
CONSUMER STAPLES
1.92%
ENERGY
0.18%
REAL ESTATE
0.13%
Top 10 Holdings
MonthlyQuarterly
Represents 38.51% of Total Net Assets
As of
9/30/2021
Microsoft
7.02%
Amazon.com
5.51%
GE
4.48%
PNC Financial Services Group
4.03%
Yum! Brands
3.16%
Thermo Fisher Scientific
3.11%
Alphabet Class C
3.08%
UnitedHealth Group
2.98%
Marsh & McLennan
2.70%
Humana
2.43%

+1

OK, with a search I did find the following info from Ameritrade. It apparently deals with margin purchases, which I never even consider, so it's probably a logic "don't care".

Maintenance Requirements on Stock
How are Maintenance Requirements on a Stock Determined?
In accordance with the rules of the exchanges, TD Ameritrade places “Initial and Maintenance” margin requirements on accounts. These requirements dictate the amount of equity needed in an account in order to hold and create new margin positions.
All broker/dealers, including TD Ameritrade, Inc., reserve the right at any time to adjust minimum maintenance requirements. This adjustment can be done on an individual account basis as well as on a stock-by-stock basis, depending on a stock's trading volatility and other factors. Your account may be subject to higher margin equity requirements based on how market fluctuations affect your portfolio.
Below are the maintenance requirements for most long and short positions. However, concentrated positions and certain stocks may have special requirements between 35% and 100%.
Non-marginable stocks cannot be used as collateral for a margin loan. Likewise, you may not use margin to purchase non-marginable stocks.

Lost 18.14% in 1Q 2020, vs 10.94% for FMSDX .

WBALX lost only -8% in 1Q 2020.
But....FMSDX has a 3 year annual return of close to +17%, versus TSHIX at 12.5% and WBALX at 10.6%.

Schwab has this note regarding TBUX:
"Please Note: TBUX has a special maintenance requirement of 100%"
Can anyone tell me what that means?
Thanks- OJ

Lost 18.14% in 1Q 2020, vs 10.94% for FMSDX .

Nothing like transposing characters. My error.
Looks like a pretty good fund. The only thing that jumps out on a cursory look is that it is very deep into junk bonds - more than half are B rated, another nearly 10% below B.

The higher rates only benefit newer issues (at higher rates). The existing holdings (that have lower rates) become increasingly less attractive.

Even if the fund holds

floating rate securities / adjustable rate mortgages?

Possibly. ARM funds were being launched left and right in the early 90s. And then they began dropping like flies as intererst rates rose.

In 1995, directors of the T. Rowe Price Adjustable-Rate U.S. Government Fund voted to broaden its investment policy and to change its name to the T. Rowe Price Short-Term U.S. Government Fund.
...
While the original ARM fund concept may have been valid, Randall Merk, director of fixed income investments for American Century, says, the industry "badly overstated" the protection such funds can afford shareholders during periods of rising interest rates.

https://www.orlandosentinel.com/news/os-xpm-1997-06-22-9706201623-story.html