resolved by using following query
select * from
(select * from
(select brcd, round(sum(outamt)/1000,0) amt from cis where assetcd !='IR00001'
group by brcd order by amt desc) where rownum <11) a
inner join
(select brcd,round(sum(outamt)/1000,0) amt2 from cis group by brcd) b
on a.brcd=b.brcd
order by amt desc
;
any better way to do so.