trigger InsertingBU on Opportunity (after update) {
  Set<Id> accountIds = new Set<Id>();
  for(Opportunity o : Trigger.New)
     accountIds.add(o.AccountId);
  list<Business_Unit_Company__c> BUCUpdate = new   list<Business_Unit_Company__c>();   
  list<Business_Unit_Company__c> Bus1 = new list<Business_Unit_Company__c>();
  Map<Id,Business_Unit_Company__c> bus = new Map<Id,Business_unit_Company__c>();
  set<string> busStage = new set<string>();
  for(Business_Unit_Company__c bu : [Select Business_Unit__c,Company__c,Stage__c from Business_Unit_Company__c where Company__c IN: accountIds]){
      bus.put(bu.Business_Unit__c, bu);
      busStage.add(bu.Stage__c);
      }
  for(Opportunity o : Trigger.New) {
    if(o.Opportunity_Business_Unit__c != null && bus.get(o.Opportunity_Business_Unit__c) != null){

    if((busStage.Stage__c == 'Closed Lost') && ((o.StageName =='0 - Existing Customer Lead') || (o.StageName =='1 - Prospecting') || (o.StageName =='Qualification') ||(o.StageName =='2 - Client Interaction') ||(o.StageName =='Needs Analysis') ||
       (o.StageName =='3 - Quoting Client') ||(o.StageName =='Value Proposition') ||(o.StageName =='Id. Decision Makers') ||(o.StageName =='Perception Analysis') ||(o.StageName =='4 - Buying Signals') ||
       (o.StageName =='5 - Quoted/Final Negotiation') || (o.StageName =='Proposal/Price Quote') || (o.StageName =='Negotiation/Review'))   
       ){
       Business_Unit_Company__c bu1 = new Business_Unit_Company__c();
       Bu1.stage__c='Closed Lost';
       Bu1.Company__c=o.AccountId;
       Bu1.Business_Unit__c= o.Opportunity_Business_Unit__c;
       Bus1.add(bu1);
       break;
       }else if( (bus1.Stage__c== 'Open') && (o.StageName=='Closed Lost')){
       Business_Unit_Company__c Bu2 = new Business_Unit_Company__c();
       Bu2.stage__c='Closed Lost';
       Bu2.Company__c=o.AccountId;
       Bu2.Business_Unit__c= o.Opportunity_Business_Unit__c;
       Bus1.add(Bu2);
       break;
       }else if((bus1.Stage__c== 'Closed Lost') && (o.StageName=='Closed Won')){
       Business_Unit_Company__c Bu3 = new Business_Unit_Company__c();
       Bu3.stage__c='Closed Won';
       Bu3.Company__c=o.AccountId;
       Bu3.Business_Unit__c= o.Opportunity_Business_Unit__c;
       Bus1.add(Bu3);
       break;
       }       
  }else{
  Business_Unit_Company__c BUC = new  Business_Unit_Company__c();
        BUC.Company__c=o.AccountId;
        BUC.Business_Unit__c=o.Opportunity_Business_Unit__c;
        if(o.StageName == 'Closed Won' || o.StageName == 'Closed Lost'){
        BUC.Stage__c=o.StageName;
        }else{
        BUC.Stage__c='Open';
        } 
        BUCUpdate.add(BUC);       
        }
 
    
                          
}
    if(Bus1!= Null)
    update Bus1;
    if(BUCUpdate!= Null)
    insert BUCUpdate;
}