He probably sells FNMA when he thinks it's time and then buys Freddie for 10 cents cheaper. Then continues to do that accumulating more shares. He probably only sells and buys a portion of his investment and holds a core position in case major news happens after hours. Many traders here do this I think. I however, just buy as much as I can each month regardless of price (all between 0.25 and 3.00 over The years) as I think the end result is worth it. I haven't sold a share of either FnF. Best of luck