The uranium bubble of 2007 was a period of nearly exponential growth in the price of natural uranium, starting in 2005[2] and peaking at roughly $300/kg (or ~$135/lb) in mid-2007.[citation needed] This coincided with significant rises of stock price of uranium mining and exploration companies.[3] After mid-2007, the price began to fall again and at the end of 2010, was relatively stable at around $100/kg.[4]