BOXX vs. XBOX vs. CBOX vs. XCSH – Box Spread ETFs Compared

Alpha Architect created the box spread ETF space with BOXX and owned it for a few years. Now three competitors have launched in 2026 alone – XBOX from Roundhill, CBOX from Calamos, and XCSH from XFUNDS. Here I compare them and talk about which one might be best.

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BOXX vs. XBOX vs. CBOX vs. XCSH – Quick Comparison Table

Before we get into the details of BOXX, XBOX, CBOX, and XCSH, here's the quick comparison table:

Data as of September 2026.

I'll explain the impact of these numbers and characteristics in the sections below.

Intro – Why Do We Care?

If you've already read my comprehensive blog post on BOXX, you already know the pitch and the risks. If not, go read that first.

Basically, we're hoping to turn T-bills-like income into capital gains and avoid – or at least minimize – tax drag of holding an otherwise cash-equivalent position. This benefits those in higher federal tax brackets but may not help much if your state doesn't tax income, as real T-bills are exempt from state taxes. I made a calculator to assess your personal circumstances here.

BOXX has carried a net fee of 0.19% since inception in 2022, but now three new players have undercut it for basically the same strategy. So does BOXX still deserve your cash? Let's unbox the new box spread ETFs…

Unboxing the 4 Box Spread ETFs Briefly

Now let's talk about these box spread ETFs.

BOXX – Alpha Architect 1-3 Month Box ETF

BOXX is the one you've heard of and the one that started this whole category. It's the Alpha Architect 1-3 Month Box ETF.

BOXX launched in December 2022 after years of planning by the Alpha Architect crew, grew to over $14 billion in assets, and has withstood the test of time, at least so far.

It's using physically-settled SPY and QQQ contracts for the box spread trade to extract a rate resembling that of 3-month T-bills.

Again, I covered BOXX and the general idea of these products in much more detail in a separate post here.

XBOX – Roundhill Ultra Short Duration No Dividend Target ETF

XBOX is Roundhill's entry, which launched in March 2026 at a net expense ratio of 0.14%, tied for the cheapest of the bunch on paper. It's the Roundhill Ultra Short Duration No Dividend Target ETF. (No, this fund has nothing to do with the Microsoft gaming console. Cease and desist letter incoming?)

Instead of BOXX's sub-90-day ladder, XBOX reaches a bit further out to 1-6 month maturities, so it's not a perfectly apples-to-apples substitute, but that difference is arguably immaterial.

XBOX has hovered around $300M in AUM, which is not insignificant but pales in comparison to BOXX's $14 billion. It has also been gradually losing assets, not gaining, which doesn't exactly inspire confidence.

XBOX is also set to be renamed the Roundhill Box Spread ETF around October 2026, which is less of an awkward mouthful than its current name.

CBOX – Calamos Tax-Aware Collateral ETF

CBOX is Calamos's answer. It's the Calamos Tax-Aware Collateral ETF. It launched in April 2026 at a net expense ratio of 0.14%, essentially tied with XBOX for cheapest and 5 basis points under BOXX, with that discount locked in through December 2029.

CBOX has attracted an impressive $1.6 billion in assets and it hasn't even been around a year yet. As such, this is arguably BOXX's closest competitor.

XCSH – XFUNDS 1-3 Month BOX ETF

XCSH is the new kid, having launched in August 2026 by XFUNDS (sub-advised by Nicholas Wealth on Tidal's infrastructure).

I'm assuming the ticker could be read as “X-cash,” but then don't confuse that with “X Money,” the X.com digital savings wallet.

XCSH undercuts BOXX's fee by 0.01% for a 0.18% net expense ratio, but at the time of writing in mid September 2026, it only has about $10M in assets.

Thin volume means wider spreads, which eats into the yield and tax advantage this whole category is built on. There's nothing wrong with XCSH structurally; it's just too new and too small to recommend over the others as of now.

Honorable Mentions – CMBO and LBOX

Honorable mentions go to CMBO, the Wayfinder Dynamic U.S. Interest Rate ETF, and LBOX, the GraniteShares Short Term Box ETF.

CMBO launched in November 2025, has a net fee of 0.15%, and targets the longer end of the T-bills curve around 12 months.

LBOX launched on August 24, 2026, with the lowest fee here at 0.13%.

Unfortunately, CMBO and LBOX have a mere $3 million and $1.5 million in assets respectively and are thus at risk of closure at this time, so I can't seriously consider them yet.

Similarities, Differences, and Considerations

Now we'll touch on the similarities, differences, and salient considerations among these various box spread ETFs.

Similarities

Speaking broadly, all these funds are doing essentially the same trade with the same instruments under the hood and even have some of the exact same language in their prospectuses.

They all lean on the same tax theory and execute the same way. You might think one of these funds does it safely and one does something more risky but that's not the case. They converged on the same idea and the same structure. I suppose that could change in the future for some unknown reason, but for now they're roughly the same thing in different boxes, pun intended.

Differences

We should probably be more concerned with the differences. The main differences here are maturity, liquidity, fees, and track record.

The first difference is the slightly different points on the T-bill maturity curve. BOXX, CBOX, and XCSH are 3 months while XBOX goes out a bit further to 6 months. This is a minor difference.

Liquidity in this context is going to come with AUM. For the buy-and-holder, it's probably fine for BOXX, XBOX, and CBOX, and potentially questionable for XCSH right now since it just launched a month ago. All else equal, more AUM means smaller spreads here. So BOXX is inarguably the tightest, followed by CBOX, followed by XBOX.

The obvious big difference and likely the most salient concern for most people is fees. BOXX has held the throne for a while with a net fee of 0.19%, and now a few other players have entered the arena at lower costs. Should you incur capital gains taxes to switch to a new fund that is cheaper by a few bps? Probably not. But if you're starting out in this space, are the new players worth your consideration? Maybe. I already own BOXX so I'd incur capital gains taxes if I wanted to switch.

Will Alpha Architect lower BOXX's fee to remain competitive? Only time will tell.

History and Regulatory Status

Now let's talk about history, which I actually think is a major consideration here. Alpha Architect literally wrote the book for this space with BOXX. This usually might not mean much in other categories but I think it does in this context given the questionable regulatory oversight of the IRS in regards to the box spread ETF wrapper that I discussed in detail in my BOXX post.

I'd be remiss not to at least briefly mention the regulatory situation here if you're not already aware. Every fund in this category relies on the same contested reading of the U.S. tax code, specifically whether anti-conversion-transaction rules could eventually recharacterize this capital gains as ordinary income retroactively. This concern is nontrivial but is also arguably overblown. No court ruling or IRS guidance has actually resolved this either way, for any of these funds, though Treasury did finally explicitly mention in July 2026 that the category is on its radar. What that actually means for shareholders, if anything at all, remains to be seen.

I trust Alpha Architect's expertise and authoritativeness in this arena and I think that trust is worth more than saving a few basis points going with a newer fund, at least at this time. Let's also say hypothetically the IRS does come knocking one day. I suspect AA would have more resources and knowledge with which to navigate that compared to these other providers.

So do your own due diligence and proceed with cautious optimism. The full discussion of this regulatory concern is beyond the scope of this post but is included in my separate original post on BOXX.

Which Box Spread ETF Is Best?

I wasn't even going to opine much on that question at all and then I realized I'll immediately get that question in comments and emails if I don't answer it here. But as you've seen based on the above discussion, the answer is not a simple one.

CBOX seems like the obvious budget pick with its being tied for the cheapest at 0.14% while also having substantial assets at $1.6 billion. Unless I'm missing something, I see no reason to choose XBOX, XCSH, CMBO, or LBOX over it at this time. So if I were starting fresh and wanted the lowest fee, I'd consider CBOX.

As I hinted at, BOXX is the stalwart default that now costs a little more comparatively. I think one could reasonably argue you're paying 0.05% more for greater expertise, but that's admittedly hard to assess and quantify, and it may never tangibly impact your decision. I've got significant cap gains sitting in BOXX so I'm not interested in switching.

In summary, I think it distills down to this question: Do you want the newer, cheaper option or the established, more liquid one?

Do you own any of these box spread ETFs or do you plan on buying any? Let me know in the comments.

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