NEW YORK ( TheStreet) -- On June 28, gold prices hit their lowest levels in nearly three years, just above $1,180 per ounce.This bear move wiped out $66 billion in investor holdings since the metal hit its all-time highs in 2011. What's worse, current values suggest that some mines will be unable to break even without something in the way of a corrective rally. Last month, a string of downgraded forecasts (from UBS, Morgan Stanley and BNP Paribas) put many investors on the defensive, and it now appears there is nothing that can stop prices from heading lower into the later parts of this year. Key factors driving this decline can be seen in the fact that the eurozone debt crisis and macroeconomic risks as a whole have largely stabilized. This removes some of the safe-haven attraction that gold tends to provide. In addition, real bond yields experienced sharp increases in the second quarter. The 10-year Treasury yield hit highs above 2.6% this month (an increase of more than 1% since the beginning of May). Rising yields lead to higher opportunity costs in holding assets like gold, which offers no yield. Gold in the second quarter saw its biggest declines since the U.S. dollar was taken off the gold-standard in 1971. Those holding the SPDR Gold Trust ETF ( GLD) have seen losses of more than 25% this year alone.