So I (finally!) see IOFIX available NTF to me at TIAA. I read up on the fund in this months Commentary. Then read up on literature. One thing didn't quite understand is why the "opportunity set" for this fund might be finite. And related to that, wanted to ask if it was "too late" to buy the fund. Is there some expectation fund might tank in future, or is the suggestion manager might liquidate the fund in future?
If you can please clarify.

For those who are interested in investing in a Traditional IRA, that is where the majority of my investment assets are located. I try to use a bit more risky, and higher TR options than in my taxable account. However, I am very conservative, focused on preservation of principal, and using funds that will have a good chance at recouping my RMD distribution each year. In 2019, we had a very good market, and I was able to recoup my RMD, plus increase my overall IRA investment total by a healthy amount. I tend to use a large number of multisector bond oefs in my IRA. I have categorized multisector bond oefs that I follow in the following manner:
Conservative Multisector bond oefs: ANGIX is one of the more conservative lower risk multisector bond fund, and has been around for many years. VCFAX/VCFIX is probably my favorite fund, and has had a solid but shorter history than some other funds. IISIX/ISIAX is actually a nontraditional bond oef, but I consider it a very low risk multisector bond oef. I also include PIMIX/PONAX in this conservative category, have held it for many years, but it has become a bit more inconsistent in recent years, as it has had to branch out into more risky HY and EM bond categories, to help deal with huge AUM--it use to be a predominantly mortgage oriented fund with an emphasis on nonagency mortgages, but not so much anymore.
More risky but attractive multisector bond oefs: PUCZX is one of the more interesting funds, with a very attractive total return history--it use derivatives heavily and has a little higher SD than the more conservative bond oefs. JMSIX/JGIAX is also an interesting fund, highly recommended at Schwab because you can get the Institutional share class very cheaply--its performance history is a bit inconsistent, but it has been doing well this past year. JMUIX/JMUTX is also a very interesting fund, with a great TR history, and a very strong 2019--it has more appeal to me than PUCZX and JMSIX because it appears a bit less risky. PTIAX is a barbell type fund, focusing on longer term Munis and Nonagency mortgages--it has some inconsistency in my opinion, probably because of its barbell holdings. PTIAX pays a nice yield. IOFIX is a multisector bond fund, that is relatively new, and has phenomenal TR history, but it focuses primarily on one risky mortgage category, so I consider it more risky but very tempting.
Not sure what others are doing in this category, but I am "considering" stepping up my risk a little, but not considering any major changes in my overall very conservative holdings. I have this love/hate relationship with PIMIX, which I hold in a small portfolio percentage, and I am trying to determine whether I want to increase my investment in this fund, or possibly add a new fund I don't currently hold like JMUTX.

IOFIX is indeed a niche-fund. I would not however accuse them of doing things backhanded but rather just differently than all the others. I'm providing just the facts below, you can Google the heck out of it on your own. Numerous articles/opinions out there.
IOFIX Fact Sheet

Thanks, @JohnN. I just looked. GOOD prospects. Vanguard customer service is not the best, though, so I hear.... @Mark, is IOFIX not a niche-fund, doing backhanded things to generate its profit?

I own 6 bond funds (words that I never ever expected to hear coming out of my mouth) but all in an Roth IRA to avoid paying taxes on the income generated by them. All have greater than 4% yields, 5 of them twice as much. (FWIW: IOFIX, BIT, PCI, PDI, PFN, PTY). I am not suggesting that you buy any of them, especially the CEF's.
For your "taxable" account might you not fair better by looking at a muni bond fund or something like a dividend growth fund (e.g. VDIGX, but there are many others) where the income might be at least partly qualified and thus possibly sheltered from the tax man? I'm guessing that you 'need' the income in your taxable side and prefer not to draw down your IRA account(s).

Well, actually: I won't live forever. I have thought and thought, and waited and waited to pull the trigger on my T-IRA. Drawing-down the T-IRA just 3k or 4k each year actually gives me a 50-year window of time before it's all converted from tax-sheltered into whatever new taxable accounts I create. Wifey's agenda is NOT to stay Stateside after my demise. The more I put into a taxable account, the more she'll have readily available, without worrying about the arcane, convoluted tax rules. Whatever she inherits within a T-IRA, she'll have to wait until 59 and a half to get at it, without burning up a quick and instantaneous 10% tax penalty.
This is do-able, and the more she has sitting in a taxable account, the better. At this point, we don't need to worry much about sheltering big profits and worrying about a sizable income. We've relocated to where we want to be for now. A dream come true, though we don't by any means live in a palace. Extended family is here to be of help, and they're great. Wifey will get a car, I won't even bother. 4 cars, in a single household. People are busy, just not ME. I can use my bus pass anytime to see ALL of Oahu, unlimited. I could circumnavigate Oahu on the bus every single day if I want! The senior yearly bus pass is less than one-twelfth of a standard annual pass. That's the difference between groceries or no groceries for over a month. Can you see me smiling from here?

I own 6 bond funds (words that I never ever expected to hear coming out of my mouth) but all in an Roth IRA to avoid paying taxes on the income generated by them. All have greater than 4% yields, 5 of them twice as much. (FWIW: IOFIX, BIT, PCI, PDI, PFN, PTY). I am not suggesting that you buy any of them, especially the CEF's.
For your "taxable" account might you not fair better by looking at a muni bond fund or something like a dividend growth fund (e.g. VDIGX, but there are many others) where the income might be at least partly qualified and thus possibly sheltered from the tax man? I'm guessing that you 'need' the income in your taxable side and prefer not to draw down your IRA account(s).

If you open and read this, there is an image of the guy that wrote this blog and he looks like he may have been about 15 years old when REITS crashed in 2007-2009, so I don't think he understands the pain REIT investors felt at that time. I don't know how he can make this summary statement below. If I look at the Vanguard ETF for REITS, VNQ, it lost 70%+ peak to trough during the great recession. Would that be considered a bond alternative with less risk for retirees?

REITs are a viable alternative to retirees and other income investors who desire greater income without having to take significantly more risk.

The above and other posts by MikeM are what I have been saying for years. If I want higher income I use funds like Multisector funds such as IOFIX and PIMIX. If you are looking for high income + a good total return, look no further than PCI,PDI and other Pimco CEFs.
My opinion is that PCI will have a better performance than stocks in the next 5 years and if you are a trader you can avoid the big losses too by using weekly MACD as a good indicator. See PCI (chart) and use it to buy PCI when weekly MACD is positive and sell when it's negative

@syzygy
I am still waiting for 2019 IOFIX numbers, if any. Have not seen any 2019 numbers yet.
They have only 2016, 2017 and 2018 on their website.
I called BRUFX on Friday; no numbers yet also.

Alphacentric funds: http://alphacentricfunds.com/wp-content/uploads/2017/11/AlphaCentric-Distributions-2017-11-21-EST.pdf
Generally all share classes of a fund have the same cap gains distributions, because all shares represent the same fractional interest in the fund's portfolio. Only the income divs tend to be different for each share class because the expenses are paid first out of div income.
Since IOFAX projects no cap gains distributions (as of Nov 21), you can figure that the IOFIX share class is likewise not planning a cap gains distribution.

@TheShadow - Many thanks! Saved me a lot of time and moola.
Does anyone know if IOFIX plans a year-end capital gain distribution?

I too am glad to see the emphasis on Liquidity. It was probably not responsible for the "flash crashes" of ETF prices some of us can remember but that is a good example of what it might look like if everyone in some of these junk heavy bond funds headed for the door at the same time.
Many of the positions are priced by proxy "fair value" but that number will be meaningless.
However many of the non traditional income funds profiled here ( I suspect widely used by MFO members) like ZEOIX, RPHYX, RCTIX, IOFIX PFUIX are loaded with these securities.
Does anyone have an idea how to predict in even a vague what might happen to even very short duration junk bonds or RMBS in such a situation?
ZEOIX dropped almost 1% in couple of days last December, a fact the fund said would soon be recovered because the bonds were soon to come due at par. When redeemed at par the NAV was restored.
Is duration then some protection for liquidity issues like this? IF you trust your fund manger to avoid defaults, and hope that she/he doesn't have to sell at reduced prices before bond redemption. I have no idea how a mortgage backed security would trade in that situation.

The author of the link=https://www.barrons.com/articles/bond-funds-yields-treasurys-pimco-junk-duration-51573230142?refsec=bonds
Is comparing PIMIX=Multisector fund to Investment Grade funds which is not correct.
MS funds (IOFIX,JMSIX) + HY (ARTFX) + EIFAX (bank loans) are up in Nov and the first 3 funds are also doing much better YTD.

PIMIX lost its mojo since early 2018. In 2019 PIMIX managers continue to make fatal mistakes which put its performance in the bottom 10% for YTD until several weeks ago. The managers finally got it right (about rising rates) but it still ranks in the bottom 20%. I think its best days are over, PIMIX may still be an above-average fund
but not in the top 10%. PIMIX was my biggest % fund for years (40-50% and more) and the easiest fund to hold. In the last year I have been using JMSIX,EIXIX and IOFIX instead.

U.S. bond prices I follow for reference peaked around Sept. 3. This includes gov't. issues, broad based IG corp. and high yield munis. IOFIX referenced by @Junkster , and a decent HY fund of ARTFX continues an up trend from Sept. 3, but the gains remain less so than from the beginning of the year. A general overview of U.S. bonds from Sept. 3 indicate up and down moves that were of consequence for short periods, but as of Nov. 6 this 2 month period is FLAT for price profits.
I suggest a bottom in pricing that may be held could be the result of international monies wanting to hold bonds, but will continue to stay away from the negative yield world. A 10 yr Treasury may not look like much here at 1.8% yield, but is a decent spread from a negative -.5% in Euroland.
My 2 cents about the current bondland.

@catch22, there has been a huge move in bund rates the past month. The German 30 year has gone from negative to positive. The 10 year at -0.24% should follow. Our 10 year is at 1.96 today. I can get 1.80 from a Fidelity money market fund. I think the current steepening of the yield curve has only just begun. But we shall see. I am no expert. Then again, the last expert I referenced a month or so ago said you better buy up all the bonds you can get, especially the 30 year when it was at 2.01%. Not the best advice so far.

U.S. bond prices I follow for reference peaked around Sept. 3. This includes gov't. issues, broad based IG corp. and high yield munis. IOFIX referenced by @Junkster , and a decent HY fund of ARTFX continues an up trend from Sept. 3, but the gains remain less so than from the beginning of the year. A general overview of U.S. bonds from Sept. 3 indicate up and down moves that were of consequence for short periods, but as of Nov. 6 this 2 month period is FLAT to negative, for price profits.
I suggest a bottom in pricing that may be held could be the result of international monies wanting to hold bonds, but will continue to stay away from the negative yield world. A 10 yr Treasury may not look like much here at 1.8% yield, but is a decent spread from a negative -.5% in Euroland.
My 2 cents about the current bondland.

Not sure bonds (except for maybe high yield) are the place to be. 2020 may be the reverse of 2019 as the 10 year moves to the 2.50 to 3% range. The negative rate scenario may also be a thing of the past in places like Europe next year. End of the day my only holding will be IOFIX but lightening up a bit there too just in case. The fundamentals still look compelling for that niche bond fund but never know when investors will sell en masse anything bond related.

Tentatively selling two junk bond funds tomorrow and rolling part of the proceeds into IOFIX. That will take me from 79% to 83% in IOFIX. Last November was when this fund had its largest drawdown. Hopefully this November won’t be a repeat. Back then you had equites tumbling, credit spreads blowing out, and short term rates on the rise. I doubt in my lifetime I will ever again find such a steady eddie of a fund. Also holding two small positions in preferred funds APEIX and PFINX.

My usual comment.
For most investors, buy and hold a simple target fund is one of the best. I believe you can do worse.
For above-average knowledge investors, there are several other good options.
I see stocks as a simpler portion of one's portfolio. The US LC is the dominated category and SPY/VTI is a pretty good risk-adjusted index. The biggest difference is the bond portion and the older you get the more you should pay attention. For most, it's several years prior to retirement and thru retirement.
Bond land has opportunities such as Multi sector and Non trad bond OEFs and all the way to leverage FI CEF. These funds have much higher dist and in most cases reasonable risk attributes (SD, Max draw, Sharpe, Sortino). Examples: PIMIX,SEMMX,IOFIX,JMSIX...PDI,PCI.
For about 20 years I have used best risk/reward funds.
I can name several for stocks/allocation...PRWCX,USMV,SPLV and maybe DSEEX, AUEIX...recently I looked at international stocks and came up with MFAIX/MFAPX.
Most/all of these articles, opinions and research papers are discussing simple bond funds which are planes without a pilot.

Thank you to all for responding. I am going to consider EIXIX.

Please note most of its outsized YTD returns in EIXIX occurred the first four months of its existence. The past 6 months it has been mediocre at best compared to IOFIX among others. You seem to like the non agencies. You might want to check out DPFNX. It gets no mention but a real steady eddy in the non agency sector. As detailed in the past, I paired it with IOFIX in 2017 and part of 2018. Haven’t been in it this year but that may change soon.

SEMPX was a big part of my portfolio in 2018 but none in 2019. YTD at 3.8% is not good when many made a lot more. Look at direct securitized rivals such as IOFIX,EIXIX and VCFAX. I know SEMPX has low duration and very low SD. SEMPX is pretty good as a cash sub for investors who understand its higher risk/volatility. T
The lowest SD in this group is SEMPX and then VCFAX which is more diversified.
If you want more performance with higher SD then IOFIX,EIXIX(new fund with very small AUM).
BTW, from their last top (1-2 weeks ago) IOFIX,EIXIX held better than SEMPX,VCFAX.