If M* can be believed the SEC yield for SPAXX is 4.31 to 4.29 for RPHIX though the total return for the latter is still slightly ahead.

30 day and 7 day SEC yields measure different things.
The yield for MMFs including SPAXX is the average current (i.e. distribution) yield (before compounding). The yield for other funds is a 30 day average yield approximating YTM, i.e. projected future total return.
To simplify the non-MMF case, consider an OEF holding a single bond to maturity. If that bond matures in one year, pays a 7% (of face value) coupon semiannually, and is priced at $1,020. Then its YTM (SEC yield) is 4.902%. Its distribution yield is 7% x $1000/$1020 = 6.863%.
http://www.moneychimp.com/calculator/bond_yield_calculator.htm
SPAXX's 7 day yield as of 10/25/24 is 4.49%, compounding to an annual yield of 4.59%.
https://fundresearch.fidelity.com/mutual-funds/performance-and-risk/31617H102
I'm not sure where you found any SEC yield for SPAXX on M*. Here's M*'s page for the fund: https://www.morningstar.com/funds/xnas/spaxx/quote
Likewise, I can't find the 30 day SEC yield for RPHIX on M*. Nor can I find it on RiverPark's site. The best I can find there is an SEC yield of 4.61% as of June 30th. While I do find an SEC yield of 4.29% at Schwab.
However, going by that source, Schwab also gives the current (7 day SEC) yield of SPAXX as 4.49%. Same as Fidelity (to be expected).
My bottom line: RPHIX has outperformed SPAXX over the past 1 month through 9/30, I believe, which I'll take as approximating current performance. In October (through 10/25) RPHIX has returned 0.31% (per M* graph). Without compounding, that's 4.5%, still slightly outperforming SPAXX.
https://fundresearch.fidelity.com/fund-screener/results/compare/short-term-perf/averageAnnualReturnsYear3/desc/1?order=&tickers=RPHIX,SPAXX

And 7-day for SUTXX at Schwab is 4.68%, YTD = 4.08%, also as of 10-25-24.

Hi @WABAC
The current 7 day yield for the Fido MM, SPAXX = 4.49%. Down from last weeks 4.52% yield.
YTD return is indicated at 4.10%, as of 10-25-24

Here is another article:
https://www.thinkadvisor.com/2024/10/25/vanguard-to-close-legacy-mutual-fund-platform-by-end-of-2025/

As mentioned by @Catch22 in this thread, the yield on the 10 year treasury has increased 17.4% since September 16.
Under the circumstances, what have you done for me lately means between the last week and the last four weeks (YMMV.) Over that time period some very nice short term funds are under-performing SPAXX. If M* can be believed the SEC yield for SPAXX is 4.31 to 4.29 for RPHIX though the total return for the latter is still slightly ahead.

Well. I won't argue with the numbers, then. Yes, my two junk funds are TUHYX and PRCPX. The former is two and a half times bigger than the latter. And I also hold Investment Grade WCPNX. I got into my junk just exactly at the wrong time, before the Fed's rate hiking cycle. I rode the buggers down, then back up. Reinvested all profit. I'm ahead of the game by now. Since 2018, there have been 2 terrible years, one of them being the historically putrid year of 2022. And PRCPX: right now having its worst year since 2015.
Funny, how Morningstar's performance charts don't look like they match the actual sadistics. But it's Morningstar, so... I've looked and looked for similar yields elsewhere. I'm not married to these two, but I want to discover something else that looks better to me, before I make a move. If The Fed reduces rates again, I suppose these two will benefit, like all the others.

@Crash, I know you are a big proponent on yield. Myself, it's all about total return. And, I'm a graphic trend person. Here is some total return data for 5 of the funds mentioned here. I'll give total accumulative return starting from 2021, 22, 23 and ytd 24.
from 2021 to present:
DHEAX +14.9%
WCPNX +1.7
RPHIX +16.5%
CSOAX 21.2%
BBBMX 12.8
2022 to present
DHEAX +12.5%
WCPNX +0.3%
RPHIX +14.2%
CSOAX 15.2%
BBBMX 11.7%
2023 to present
DHEAX +16.4%
WCPNX +10.3%
RPHIX +10.t%
CSOAX 22.1%
BBBMX 12.6%
2024 to present
DHEAX +7.5%
WCPNX +3.4%
RPHIX +4.7%
CSOAX 7.4%
BBBMX 5.3%
I'm certainly not a bond expert, nor do I understand categories and duration very well, but I do understand total return as viewed by graphics. I guess my only point here is a fund's total return is more important that a funds yield. You will also see in the picture in the link below which funds had more volatility getting to the end results.
https://stockcharts.com/freecharts/perf.php?DHEAX,WCPNX,RPHIX,CSOIX,BBBMX

@Crash - you don't name your two funds here. But the only taxable bond fund with a 2.49 year effective duration (per M* screener) is TUHYX. The only bond funds with a 2.68 effective duration are PRCPX, RNOTX, and MHCAX.
Ultra low volatility? Five year figures are:
RPHIX: 1.00
FLRN: 1.98
WEFIX: 2.47
FPNRX: 2.52
BBBMX: 2.56
MHCAX: 8.25
RNOTX: 8.28
PRCPX: 9.28
TUHYX: 10.41
Max drawdowns? Again over five years:
RPHIX: 1.09%
FLRN: 3.31%
WEFIX: 4.34%
FPNRX: 4.24%
BBBMX: 4.07%
MHCAX: 12.62%
RNOTX: 13.58%
PRCPX: 13.98%
TUHYX: 17.60%
How about churn? Current turnover figures are:
MHCAX: 20%
BBBMX: 22%
PRCPX: 36.20%
WEFIX: 37%
FLRN: 40%
FPNRX: 50%
RNOTX: 75%
TUHYX: 87%
RPHIX: 372%
BBBMX looks better and better.

https://www.hawaiinewsnow.com/2024/10/25/dozens-hawaiian-airlines-employees-separate-with-company-following-merger/
(Irritatingly loud start on the vid with the fabulous news announcer SCREAMING the news.)

@msf In your scenario it makes a bit more sense, but in my case it was more like I had a limit for 200 shares @ $50, got filled for 100, and the next trade came in for 50 shares @ $49.90. So my standing order could have absorbed the entire block with some room + the price difference was a little bit more appreciable...

It's not hard to construct sequences that could account for this. For example, suppose the security is trading at $50.10 when someone enters a limit order to buy 50 shares @ $49.90. Then you enter your limit order to buy 200@50. No sell orders at market price come in.
The next sell order entered is a limit order of 100@$50. Yours is the only open buy order that will meet that price, so you get the 100 shares. You have a remaining order to buy 100@$50.
The next sell entered is a limit order of 50@$49.90. Perhaps the seller entered a price lower than what you were offering because they were afraid that your offer would be snatched by some other seller swooping in and wanted to make sure their sale went through. Perhaps the seller didn't look at the depth of book and just extrapolated the sale price ($50.10, then $50.00, then $40.90). In the end, the actual reason why the seller placed the limit order at $49.90 doesn't matter.
There are two open buy orders that could purchase those 50 shares at $49.90. First one (not you) wins.

"High Yield Spreads are now at their tightest levels since June 2007 (2.89%) and Investment Grade Spreads at their tightest levels since March 2005 (0.83%). Bond investors are reaching for yield and behaving as if there will never be a default cycle again."

I moved a portion of floating rate bonds to investment grade bonds several months ago in light of the spread is getting smaller. So far the floating rate bonds keep on moving up while the IG bonds stay flat or went down. Go figure! The economy seems to moving along well, so I pause…

I listened to a very tiny little bit of it. They were talking about how the 2014 predictions said small cap were going to do better than large cap over the next 10 years LOL. I then closed it.

backtesting is so often comical

@msf In your scenario it makes a bit more sense, but in my case it was more like I had a limit for 200 shares @ $50, got filled for 100, and the next trade came in for 50 shares @ $49.90. So my standing order could have absorbed the entire block with some room + the price difference was a little bit more appreciable... Would you still feel the same about the hypothetical $100/$1 split I discussed with the trading rep?

footnote "32. Credit metrics and yield per turn of leverage for CrossingBridge Nordic Core Value Positions reflect 30 dollar-weighted Nordic positions, aggregating $211.8 mm in market value, held in CrossingBridge portfolios as of 9/30/24 excluding short term and investment grade bonds (4 positions with market value of $39.5 mm as of 9/30/24) and stressed/distressed credit opportunities (11 positions with market value of $33.1 mm as of 9/30/24)."
That is nearly $300M in Nordic bonds as of 9/30, a significant portion of total AUM. Anyone interested in the composition of each of the funds, pl visit the fund site. I superficially look at these funds occasionally and do not have a good knowledge of CB funds.
Looking forward to the breakdown as of 10/31 (first month operation) of NRDCX into the three categories of Nordic bonds mentioned in the footnote.

Reaching for yield segment says stay away from high yield, rather take risk with equities.
Pl share if you listened to the prognosis for next 10 yrs. It is 15 min long.

The Week in Charts (10/25/24)
The most important charts and themes in markets and investing, including:
00:00 Intro
00:35 Topics
02:00 How Everything Could Change over the Next 10 Years
17:52 The AI-Driven Multiple Expansion
28:29 Reaching for Yield Like It's 2007
35:00 Rise of the Bond Vigilantes
44:06 Stock Picking Is Hard, Netflix Edition
46:09 Are Workers Today Better off Than 50 Years Ago?
Video
Blog

Thanks @linter. Sorry for the trouble.
It is postmortem from me but is it possible to get around the rule by trying to buy in another account at Fidelity? I know the TF is a full $50. BTW, CBYYX is NTF at Schwab. Many here have accounts at both Fidelity and Schwab for a reason - neither of them are perfect - the irritations with each are different.

Hi @yogibearbull
Yes, absolutely dramatic. I've watched percentage changes in yields ranges as another view method; versus actual pricing.
In the Treasury yield chart link I include; the UST 10 year shows the measure.
--- Sept. 16 yield at 3.62%
--- Oct. 25 yield at 4.25%
This is a +17.4% change !!!
Anyone here would be pleased with such an investment gain in this timeframe.

There is a lithium mine in Nevada which the company exploiting it claims could meet our needs. I think it’s still getting off the ground as site approval is only two years old.
https://lithiumamericas.com/thacker-pass/overview/default.aspx
Ever since lithium became “the latest sure-fire investment” about 3 years ago, the price of the substance has been on the express down elevator. M* doggedly still assigns a 5 star rating to Lithium Americas stock.

Suppose an "all or none" limit order comes in to buy 100 shares at $50. Then you place a limit order to buy 130 shares at $50.
30 shares come on the market that meet your $50 offer price. Your order is partially filled at $50, leaving a partial order open for 100 shares at $50. There is still an earlier placed order for 100 shares at $50.
Now 100 shares come on the market with an offered price of $49.99. Who gets those 100 shares? The earlier all-or-none order or your partially filled order that you placed later?
I don't know the answer to that, but ISTM that the earlier order should take precedence over yours.