How A Bond Revolution Went Mainstream

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September 20, 2018 5:56am NYSE:AGG

From BlackRock: The iShares Core U.S. Aggregate Bond ETF (AGG) turns 15 years old this month. As Karen Schenone explains, the launch and growth of BlackRock’s flagship U.S. investment grade bond ETF changed the game for investors by putting them firmly in the driver’s seat.


Bond investing has tended to keep a relatively low profile-the alleged province of “bond geeks,” lacking the splashy media coverage of stocks. While the performance of the S&P and the Dow are avidly followed, when was the last time you overheard an elevator conversation about how “the Agg” did that day?

Yet for the past 40 years, some form of “the Agg”-the Bloomberg Barclays U.S. Aggregate Bond Index-has served as the foundational benchmark for the bond portion of most U.S. portfolios. It’s the first stop for financial advisors and other asset allocators, who look at the risk-return profile of the Agg to gauge the percentage and type of bonds they should hold.

A revolutionary idea

Exchange traded funds (ETFs) that track the S&P 500 and other broad stock market indexes have been in existence for a quarter century, but until 2003 there were few options for investors to gain exposure to the performance of the U.S. Aggregate Bond Index. Instead, most people bought individual bonds or looked to actively managed funds for the bond portion of their portfolios. While each approach has its uses, there can be downsides: bond buying can be cumbersome and costly, especially for smaller investors; active funds typically try to outperform the index by over-weighting higher-yielding sectors or adjusting duration (interest rate risk).

The launch of the iShares Core U.S. Aggregate Bond ETF (AGG) revolutionized and democratized bond investing. It was the first ETF to provide all investors with a low-cost, transparent way to “own” the world’s predominant fixed income benchmark. Just like stock ETFs, shares of AGG could be conveniently traded on exchange-tapping into a ready market of buyers and sellers instead of being confined to the over-the-counter system for individual bonds. These innovations have helped AGG grow to over $56 billion in assets.

Read more from Karen.

What’s more, the fund was low cost. Originally, the expense ratio was 0.22%, which was about one-fifth the cost of the average active manager, according to Morningstar. Today, AGG’s net expense ratio is just 5 basis points (0.05%[1]). And the average bid-ask spread of AGG is just 0.01%-a fraction of the cost of buying individual bonds, using data from NYSE ARCA as of 8/31/18.

AGG snapshot

The parts of its sum

The creation of AGG provided broad bond market exposure.  Over the next few years, iShares launched ETFs designed to track the major components of the index. This made it possible to slice the Aggregate index into “sub-sector” ETFs: Treasuries, investment-grade corporates, mortgage- and asset-backed securities, and agency obligations. Like the broader index, these sub-sectors would be difficult for smaller investors to replicate on their own. Investors actively manage these index ETFs by over- or under-weighting sectors based on their goals or market views.

Agg pieFinal

 This, too, was revolutionary. The ability to break the index into smaller building blocks gave investors even more control over their bond portfolios, conveniently and cost effectively. It allowed them to adjust the interest rate risk, income potential and diversification properties of their fixed income portfolio based on their specific investment needs. Investors can also diversify outside the U.S. with the iShares Core International Aggregate Bond ETF (IAGG).

Fifteen years ago, there were only a handful of bond ETFs. Today, there are more 1,200 of them, trading in a market worth $840 billion globally (source: BlackRock, as of 8/31/2018). AGG opened the door toward a more modern and transparent bond market.

Learn more about investing with iShares bond ETFs.

Karen Schenone, CFA, is a Fixed Income Product Strategist within BlackRock’s Global Fixed Income Group and a regular contributor to The Blog.


The iShares Core U.S. Aggregate Bond ETF (AGG) was unchanged in premarket trading Thursday. Year-to-date, AGG has declined -2.87%, versus a 9.57% rise in the benchmark S&P 500 index during the same period.

AGG currently has an ETF Daily News SMART Grade of A (Strong Buy), and is ranked #1 of 41 ETFs in the Intermediate-Term Bond ETFs category.


This article is brought to you courtesy of BlackRock.


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