Stone Ridge cat bond fund hits $5bn AUM milestone, total mutual ILS assets now ~$7.6bn

The Stone Ridge High Yield Reinsurance Risk Premium Fund, the main catastrophe bond focused strategy operated by Stone Ridge, has reached a milestone of $5 billion in assets under management, while the investment manager’s AUM across its mutual catastrophe bond, insurance-linked securities and reinsurance funds now sits around $7.6 billion.

In the last quarter of record, Stone Ridge Asset Management, the New York based alternative risk premia focused investment manager, added just over 6% in assets to its three mutual 40’s Act investment funds that hold catastrophe bonds, ILS instruments and reinsurance assets.

As usual, we can only report on Stone Ridge’s two main dedicated mutual cat bond and ILS fund strategies, as well as its diversified alternatives fund, given other private ILS fund strategies are not visible to us.

Previously, as of an April 30th 2026 official reporting date, the total AUM across Stone Ridge’s mutual 40’s Act cat bond and ILS funds stood at just over $6.8 billion, then rose slightly to around the $7 billion mark by the end of June.

That $7 billion level of AUM marked a new high-point for the Stone Ridge mutual cat bond and ILS fund strategies, surpassing a level last seen in 2018.

Growth has continued and the latest quarterly reported data shows that combined catastrophe bond and ILS AUM across the same funds had risen further to $7.23 billion by July 31st 2026.

Since then, there has been a further increase seen, that takes the total to around $7.6 billion as of the end of September 2026.

At that roughly $7.6 billion level of total ILS related AUM in mutual funds, across the Stone Ridge High Yield Reinsurance Risk Premium Fund (the largest and most catastrophe bond focused strategy), the Stone Ridge Reinsurance Risk Premium Interval Fund, that invests across the spectrum of ILS and reinsurance-linked assets including sidecars and private quota shares, other collateralized reinsurance arrangements and to a lesser degree catastrophe bonds, and the cat bond and ILS component of the multi-strategy Stone Ridge Diversified Alternatives Fund, it has now increased by almost 30% in just one year.

The largely catastrophe bond focused, around 81% of assets are cat bonds, Stone Ridge High Yield Reinsurance Risk Premium Fund had reached just over $4.44 billion of assets at April 30th 2026, then grew to roughly $4.6 billion in AUM by June 30th, before reaching just over $4.74 billion as of July 31st 2026, the last official reporting date.

But, data seen by Artemis shows that Stone Ridge’s most cat bond focused investment fund grew again to around $4.9 billion by the end of August and as of this week stands just slightly under $5 billion (although may clear that milestone level in total net assets as soon as later today it seems).

The Stone Ridge High Yield Reinsurance Risk Premium Fund has now grown by more than $900 million of assets in 2026 so far and stands more than $1.15 billion larger in just twelve months.

The cat bond focused Stone Ridge mutual investment strategy is once again at its largest ever size, having grown consistently in recent years. It is one of the largest cat bond funds in the world, although has a higher allocation to certain other reinsurance instruments, such as lower-volatility sidecars and quota shares than a comparable UCITS strategy, for example.

The Stone Ridge Reinsurance Risk Premium Interval Fund, that invests across the spectrum of ILS and reinsurance-linked assets including sidecars, private quota shares, collateralized reinsurance arrangements and to a lesser degree cat bonds, stood at $1.52 billion of net assets as of April 30th, then grew to $1.53 billion by June 30th and again to $1.58 billion by July 31st 2026.

Some further growth has been seen, as data suggests the Stone Ridge Interval ILS fund is now $1.66 billion in size, as of this week.

Recall that, this interval ILS fund strategy had once been as big as $6 billion of assets back in 2018, but shrank following the loss activity the reinsurance market experienced between 2017 and 2019. This fund has now been growing steadily since 2023, as investor-mix has adjusted and they now show increasing confidence in private ILS and collateralized reinsurance again this year.

Notably, the interval ILS fund managed by Stone Ridge has now grown by around $360 million in the last year, showing recovering investor sentiment in the strategy and a desire from certain investors to access higher return potential than a cat bond focused strategy can offer.

Stone Ridge also offers to clients a multi-strat fund that includes a relatively significant proportion of ILS assets, the Stone Ridge Diversified Alternatives Fund. This multi-strategy fund began incorporating cat bond and ILS investments to its portfolio in 2023.

When we last reported, as of April 30th 2026, total cat bond and ILS investments under this multi-strategy mutual fund had reached almost $886 million.

That has now increased during the last quarter of record to $948.5 million as of July 31st 2026, which includes a $45 million cross-investment into the Stone Ridge cat bond strategy.

As a result, the direct holdings of cat bond and ILS instruments by this Diversified fund now stand at just over $903 million as of July 31st 2026, up from $842 million at April 30th. This remains flat as a component of the multi-strat fund, with ILS at around 39% of the overall assets.

Stone Ridge continues to successfully grow these cat bond and ILS investments within its mutual fund strategy range, although clearly the more catastrophe bond focused fund remains the most successful at this time.

However, the steady growth of the interval ILS fund strategy also bodes well for the manager, as this shows the continued potential of private ILS strategies for a mutual fund investor audience.

At now assumed to be well over $10 billion, Stone Ridge remains one of the largest investment managers of ILS and reinsurance assets, in AUM terms, featured in Artemis’ directory of insurance-linked securities (ILS) fund managers.