"Can anyone explain what's the reason behind the low volume lately"
For all intents and purposes, there is no market for Fannie Mae stock. Out of the 1.158 billion outstanding shares, there are, perhaps, 10 million shares out on the playground to be played with on a daily basis. The overwhelming majority of outstanding shares are locked away in the vaults of shareholders, waiting for something good to happen; like when set free from government bondage. That said, the anemic daily trading is from day traders, shorts, and the MMS swapping shares back and forth. Some days they are more playful than other days. This $2+ share price you see every day is not reflective of an unencumbered market for Fannie Mae. Out of conservatorship and free to function as a normal corporation without meddling from the government, the dormant market springs to life and considering Fannie Mae's penchant for profitability, a normal market share price would probably be $100 or more.