A forward rate describes what a year's worth of dividends, based on the single past dividend will be 1 year from now at the current PPS(price/share). So for MTGE their last dividend was .90. Four annual(Quarterly) dividends @ .9 will give 3.60(4x.9). Based on the current PPS that will actually be a 15.37% yield.
The trailing looks back in time and adds up the previous years dividends, (.2 + .8 + .9) or 1.90. Since MTGE has not been around long enough for 4 dividends it added up the only ones it could , which were three. Based upon the current PPS, that yields 8.10%.(the numbers you quoted were when we were trading at a different PPS)
You can take to the bank that MTGE will have a .9 or higher dividend declared within the next two weeks, or so, and that will give you 15.37% yield going forward, based upon .90, and 17.07%, based upon 1.00. Not bad, right?
Again, stay with the winners AGNC and/or MTGE. Sell NLY, ASAP, and buy MTGE, as soon as MTGE announces their dividend in the next few weeks.