CWB’s Convertible Bond Strategy Looks Like Bonds Until the Equity Markets Fall, And Then It Trades Like Stocks

The pitch for the SPDR Bloomberg Convertible Securities ETF (NYSEARCA:CWB) is simple: collect a coupon, keep equity upside, sit between stocks and bonds. CWB has rewarded holders nicely on the way up. The risk most owners do not price in is that when equity markets crack, CWB stops trading like a bond fund and starts tracking the stocks its convertibles can convert into. CWB is mislabeled in many portfolios, and the asymmetry is the entire story.

What CWB actually owns

CWB tracks the Bloomberg US Convertible Liquid Bond Index. A convertible bond is corporate debt with an embedded call option to convert into the issuer’s stock at a set strike. The coupon is usually 2% to 4%, and the conversion option drives returns. The fund holds roughly $5 billion in assets, charges 0.40%, and pays a distribution yield near 2.5%.

The issuer base skews heavily toward tech and growth companies, where conversion features get used. CWB’s credit exposure is a concentrated basket of equity-linked debt from issuers whose stocks move together when the NASDAQ wobbles, not the diversified investment-grade universe a core bond fund provides.

The bond floor falls out when you need it

A convertible’s behavior depends on where the underlying stock trades versus the conversion price. When the stock sits well above the strike, the bond’s delta approaches 1 and it moves nearly point-for-point with the equity. When the stock falls, the option value bleeds out and only the bond floor (the present value of future coupons and principal) supports the price. That floor sinks when credit spreads widen, which is exactly when equity markets are stressed.

CWB participates fully in equity rallies and follows equities down, just with less velocity. The bond character only shows up after the option value has been wiped out. In 2022, CWB lost roughly 17%, CWB performed worse than core bonds and only modestly better than the S&P 500. A smaller version played out a year ago: CWB fell from around $80 to about $71 last spring, roughly an 11% drawdown in about a week as equities sold off.

For context, SPDR S&P 500 ETF Trust (NYSEARCA:SPY) is up 24% over the past year and 8% year-to-date. CWB has ridden that wave, which is why holders feel comfortable today and why the asymmetric exposure is easy to forget.

What to monitor

1. SPY level and the NASDAQ-100. Any equity drawdown beyond 5% will pull CWB with it. Check weekly.
2. Investment-grade and high-yield credit spreads. The ICE BofA OAS series on the St. Louis Fed FRED site is the cleanest read. Spreads widening past 400 bps signals the bond floor is compressing.
3. VIX above 25. Elevated implied vol can briefly help convertibles by raising option value, but sustained spikes usually coincide with equity selling that overwhelms the option lift.
4. Rolling 30-day correlation between CWB and SPY. When it climbs above 0.7, CWB is functionally an equity position.

The bond-like alternative

If actual bond behavior in an equity drawdown is the goal, Schwab U.S. Aggregate Bond ETF (NYSEARCA:SCHZ) is the cleaner instrument. It tracks the Bloomberg US Aggregate, the investment-grade universe most retirees thought they were getting. SCHZ is down 2% year-to-date and roughly flat over the past year, with much lower equity correlation than CWB. The yield is lower than CWB’s distribution, but SCHZ will not move in step with the S&P 500 in a drawdown.

The bottom line

CWB is a coherent way to express a mildly bullish equity view with a coupon attached. The risk is structural mislabeling: it sits in the bond aisle and gets used as a fixed-income allocation, but its behavior in a 15% to 20% equity drawdown will look far more like stocks than bonds. Holders who understand that can stay comfortable. Holders who own CWB expecting it to cushion an equity sell-off should size the position accordingly or pair it with a true core bond fund like SCHZ.