The index-versus-active debate has been bubbling away for years. And with strong opinions on both sides, it is likely to remain a contentious issue.

The overwhelming majority of US-managed active funds have underperformed their respective benchmark across all asset classes over the past five years, according to S&P.

However, over the last decade, Standard & Poor’s has been serving as the de facto scorekeeper of this debate through the maintenance of its S&P Indices versus Active Funds Scorecard (SPIVA).

The latest results, revealed in its Mid-Year 2012 Scorecard, show that the majority of US-managed active funds have underperformed their respective benchmark across all asset classes over the past five years.

Drilling down into the data shows that within the US equity space, active equity managers overwhelmingly failed to outperform their corresponding benchmarks. Indeed, 65% of active large-cap funds lagged behind the S&P 500; 82% of active mid-cap funds were outperformed by the S&P MidCap 400; and 78% of active small-cap funds trailed the S&P SmallCap 600

The five-year data is also unequivocal for fixed income funds. In most bond categories, benchmark indices outperformed a majority of active managers.

For proponents of style box driven investing and the asset allocation framework, style consistency matters tremendously. The Scorecard shows that over a five-year horizon, barely half of the funds that survive remain consistent in their original style box.

With numbers as bad as this, perhaps it’s no surprise that over the last five years approximately 24% of domestic equity funds, 22% of international equity funds and 15% of fixed income funds have merged or been liquidated.

There was one notable exception where active managers on the whole performed well. This was in the international small-cap space. Here, over 75% of active managers managed to outperform the S&P Developed Ex-US SmallCap benchmark.