couldashoulda

Largest Bond ETF Now Trading At a Massive Discount

I believe AB is pointing out that the ETF is at a discount to the total value of the 174 bonds in the index. Each of the 174 would of course have the exposure you identify, but the article concerns "tracking error" which seems to be more prevalent in ETF's given reason volatility, especially in commodities.
Same thing as a closed end fund