What company that M1 was employed by was acquired by M2 and acquired by M3
SELECT DISTINCT ?x0 WHERE {
?x0 a ns:business.employer .
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M2 .
?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M3
}