The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.By Frank Holmes NEW YORK ( U.S. Global Investors) -- Since hitting $1,900 an ounce through the beginning of October, gold has declined nearly 11%. Over the same timeframe, the NYSE Arca Gold Miners Index lost almost 13%. That's a closer performance correlation than the roughly 3-to-1 gold equities to bullion ratio we've historically seen and could mean the miners are finally closing the gap. However, TD Securities Equity Research points out this interesting fact: Over a period of 18 months prior to hitting $1,900, gold rose 79% but TD's basket of gold equities only increased 57%. The firm says this performance gap "ranks as the worst relative performance of gold equities to gold since 2001." During the July through September period of 2008, TD Securities' universe of gold equities declined 46%, while gold bullion only lost 24%. From October through November of 2008, the same gold equities lost 37%, while gold decreased 22%. What's behind today's record disparity? Part of it may be due to the underperformance of the explorers and developers, which, TD says, "have been hit the hardest." The chart below shows gold miners by capitalization and their returns since April 2011. Explorers and developers have declined the most, losing 21%, small- and mid-cap producers have declined 6% and large producers lost 5%.