List<Business__c> businesses = new List<Business__c>();
Set<string> combineIds = new Set<string>();

for(Business__c bus : [Select Combine__c from Business__c]) {
    combineIds.add(bus.Combine__c);
}

List<Account> accounts = [SELECT ID, Combine__c, Market__c, Name FROM Account WHERE Combine__c IN :combineIds];

Business__c busRec = New Business__c();

For(Account a: accounts){
    busRec.add(New Business__c(Name = a.Name, a.Combine__c, busRec.acctId = a.ID, busRec.Market = a.Market__c));

    database.Upsert(busRec,false);
 }