It only leaves off the end of Mark’s gospel. Some people think that because that was the first gospel written, that the other gospels were contrived or something like that. It doesn’t really make any sense to me.
What do you mean by “leaves off the end” ?
Mark’s gospel in Codex Sinaiticus ends like this,
16:1 And when the sabbath had passed, Mary Magdalene and Mary the mother of James, and Salome bought spices, that they might come and anoint him.
2 And very early on the first of the week they came to the sepulcher, the sun having risen.
3 And they said among themselves: Who shall roll away for us the stone from the door of the sepulcher?
4 And looking up they see that the stone had been rolled away; for it was very great.
5 And they entered the sepulcher and saw a young man, sitting at the right side, clothed in a white robe; and they were amazed.
6 But he says to them: Be not amazed. You seek Jesus the Nazarene who was crucified; he has risen, he is not here: see the place where they laid him.
7 But go, tell his disciples, especially Peter, that he goes before you into Galilee: there you shall see him, as he said to you.
8 And going out they fled from the sepulcher; for trembling and astonishment had seized them; and they said nothing to any one, for they were afraid.