F9
When playing the root 5 ninth chord, the third finger forms a half bar across the first three strings. For ease of playing the third finger is positioned first. The thumb or the tip of the 2nd finger can be used to deaden the sixth string.
The ninth chord consists of the I - III - V - b VII - IX notes of the major scale. It can be thought of as an extension of the dominant seventh chord, with the ninth note added (in terms of the major scale, the ninth note is the same as the second: