The first one occured before the crisis. Swap traders asking money market traders to round their libor submission "the right way". That number got averaged across multiple banks, and the impact on the final fixing was likely of the order of a basis point or perhaps a fraction (per the regulator's report). 1 basis point may be small, but is a lot of money to an individual swap trader given the sort of position they must have had on libor futures (and that's money to the trader, not necessary to the rest of the bank who may have a net position the other way).
The second manipulation occured at the height of the financial crisis and is of a different nature. Because banks contributions to libor fixing were public, investors were infering from the submissions whether a bank was struggling to fund itself. At the height of the post-lehman panic, some banks decided to lower their submission to not look weak. In this case the order of magnitude would be much higher, in the 10s of basis points. You could argue the banks had a financial gain, but not from the direct impact on libor (it wasn't clear what their position was, though banks tend to be typically net receiver of libor), rather from the perception of not being in distress to investors.
The first one occured before the crisis. Swap traders asking money market traders to round their libor submission "the right way". That number got averaged across multiple banks, and the impact on the final fixing was likely of the order of a basis point or perhaps a fraction (per the regulator's report). 1 basis point may be small, but is a lot of money to an individual swap trader given the sort of position they must have had on libor futures (and that's money to the trader, not necessary to the rest of the bank who may have a net position the other way).
The second manipulation occured at the height of the financial crisis and is of a different nature. Because banks contributions to libor fixing were public, investors were infering from the submissions whether a bank was struggling to fund itself. At the height of the post-lehman panic, some banks decided to lower their submission to not look weak. In this case the order of magnitude would be much higher, in the 10s of basis points. You could argue the banks had a financial gain, but not from the direct impact on libor (it wasn't clear what their position was, though banks tend to be typically net receiver of libor), rather from the perception of not being in distress to investors.