This won’t be news to regular Alphaville readers, but portfolio trading in fixed income has morphed over the past few years from cool new trend to massive phenomenon. The impact is becoming starker by the day.
Last week Barclays published some interesting new research on the subject, with a sign-off paragraph that underlines why this is a big deal:
ETFs, systematic credit, and portfolio trading will likely create a virtuous cycle of liquidity. ETF issuers have started adding more granular products that track a particular segment of the credit market, such as maturity or rating. One likely implication of the growth of these niche ETF products is the generation of additional trading demand in the underlying corporate bonds from ETF managers that need the bonds to track their benchmarks. This could spill over to systematic credit by expanding the universe of bonds over which models scan for investment opportunities, creating demand for new volumes. Portfolio trading can deliver that liquidity in a quick cost-effective way, making systematic and factor strategies more feasible. As the barriers to entry decrease, it should be easier for new systematic investors to deploy capital, which will in turn would add volumes to the market. Therefore, we expect both systematic credit investing and portfolio trading to continue to grow together.
But perhaps we should start with an explanation for people coming cold to the subject: Portfolio trading is when someone buys or sells a huge and broad batch of stocks or bonds in one go.
In equities this has been a humdrum thing for decades, but in corporate debt it has always been tricky, given how idiosyncratic each bond can be and how they have historically traded individually by phone.
However, that’s changing thanks to the emergence of better pricing algorithms that let banks and trading shops value swaths of bonds quickly and accurately; the rapid growth of electronic trading in corporate debt; and the seismic credit ecosystem shake-up caused by bond ETFs.
Investors love this because it allows them to deploy billions of dollars quickly into a representative slice of the fixed-income market, or to raise money quickly by selling hundreds (sometimes even thousands) of individual bonds in one swoop. For the first time, you can efficiently trade the corporate debt market as a whole without using derivatives.
Just how much they love this is highlighted by this new report from Barclays. The UK bank’s thematic fixed income research team led by Zornitsa Todorova estimates that a portfolio trade now hits the tape on average every seven minutes.
That is twice last year’s pace and up 10x from 2018. And that’s just in the US.
Portfolio trades are also chunky in size. Between the beginning of January and the end of October, US portfolio trading hit $1tn, which is already comfortably a record.
If the current average monthly volume of about $100bn stays at that level the 2024 total will be $1.2tn, twice last year’s total. Portfolio trades now account for a fifth of all dealer-to-client activity — ie, between banks and asset managers and investors — up from basically zero before 2018.
Here’s how that breaks down by investment grade and high yield.
Portfolio trading explains why there’s been a surge in US corporate bond trading this year, despite the lack of volatility that normally causes spurts of buying and selling, Barclays reckons.
The average size of a portfolio trade remains around $50-60mn, and the vast majority of the individual chunks being included are smaller than $5mn. But, according to Barclays, the average number of bonds being traded has more than doubled since 2018 to 110 line items.
There are also more “mega PTs” with over $500mn being traded, which have accounted for 23 per cent of all activity in 2024. These typically happen at the end of the trading day — probably because of their close ties to ETFs, which are a crucial factor in the rise of portfolio trading (because you can exchange a representative slice of bonds for shares in the ETF).
Tellingly, portfolio trading also spikes at the end of every month, when many index funds will rejig their portfolios to reflect benchmark changes, and larger institutional investors like pension plans will make allocation changes.
Portfolio trading also seems to be ameliorating some of the liquidity problems that have blighted the fixed income markets. As Barclays notes:
Our analysis shows that many investors use portfolio trades to transact in less liquid bonds. We found that bonds traded in PTs are on average 15% to 20% less liquid compared to the average bond traded in the market (as measured by Barclays LCS, higher LCS signifies higher transaction costs and hence, lower liquidity). However, investors very rarely trade only illiquid bonds in the same portfolio. The reason why portfolio trading works for illiquid bonds is because investors combine a small percentage of illiquid bonds with liquid bonds in the same basket, effectively crowd-sourcing liquidity.
This seems to have had an almost magical impact on these less-traded bonds. The percentage of US investment-grade corporate bonds that haven’t traded a single time in a month has fallen from about 3 per cent a decade ago to almost zero today.
It’s hard to say for sure, but Barclays reckons that this is mostly because of the growth of portfolio trading.
The timing of the drop coincides with the introduction of portfolio trading and its magnitude is aligned with the quantum of bonds that only trade in portfolio trading. While it is extremely difficult to precisely attribute the direction of causality, we believe our results strongly suggest that in the absence of portfolio trading, some bonds would have traded less or would not have traded at all because it would have been very expensive to do so.
Does this mean that people will stop worrying about bond market liquidity? No, of course not. But it probably means we can worry less than we used to — or at least worry more about what happens to credit markets when they increasingly resemble equity markets.