It can be correctly said that in essence "Michael Jackson owns" only about songs that belong to Mijac Music Publishing (Mijac MP; it own by far not only Jackson-written songs, but many more major songs) -- which is 100% Michael-owned company. Sony/ATV MP is only half owned by Jackson, and that half is conditional as of now.
Both of Mijac MP and Sony/ATV MP own different kind of rights, so quantity should be carefully calculated taking that into account. See Warner-Timerlane, BMI, ASCAP sites for listings of songs in which either of two those companies has interest (aside of Sony/ATV MP site).