Three BlackRock fixed-income closed-end funds experienced notable declines in their quality rankings this week, pushing each into the market's bottom decile for operational efficiency and financial health. This shift comes as U.S. Treasury yields have been declining, causing changes across the credit markets.What Does Quality Ranking Mean?According to the Benzinga Edge’s Stock Ranking methodology, the quality score is a percentile-based measure that evaluates a fund's operational efficiency and financial he ...