thanks, are we talking about and (@min_ValuatnDt is null or a.valuation_dt >= @min_ValuatnDt) and (@thru_ValuatnDt is null or a.valuation_dt <= @thru_ValuatnDt) ? but in this case both min and thru date has been initialized.
the schema are

  CREATE TABLE "dba"."PF_Daily_Holdg_detl" (
    "Valuation_dt" DATE NOT NULL,
    "Acct_grp_ID" "TAcctGrp_ID" NOT NULL,
    "subAcct_ID" "TSubAcct_ID" NOT NULL,
    "Fi_Sym" VARCHAR(20) NOT NULL,
    "sub_acct_alias_dd" VARCHAR(16) NULL,
    "Qty" "TQty_stock" NULL,
    ....,
    "Cost" "Tmoney_2" NULL,
    ...,
    PRIMARY KEY ( "Valuation_dt" ASC, "Acct_grp_ID" ASC, "subAcct_ID" ASC, "Fi_Sym" ASC )
) IN "SYSTEM";

// *******
CREATE TABLE "dba"."account" (
    "acct_id" INTEGER NOT NULL DEFAULT AUTOINCREMENT,
    "acct_grp_id" "T__AcctGrp_ID" NOT NULL,
    ...,
    "sub_Acct_Alias" VARCHAR(16) NOT NULL,
    "Updated_By" VARCHAR(30) NULL,
    "Updated" "datetime" NULL,
    CONSTRAINT "PK_AccountID" PRIMARY KEY ( "acct_id" ASC )
) IN "SYSTEM";
// *******
CREATE TABLE "dba"."SubAcct" (
    "subAcct_ID" "TSubAcct_ID" NOT NULL DEFAULT AUTOINCREMENT,
    "Acct_ID" "TAcct_ID" NOT NULL,
    ...,
    "acct_type_short_name" VARCHAR(28) NOT NULL UNIQUE,
    PRIMARY KEY ( "subAcct_ID" ASC )
) IN "SYSTEM";

thank you, Volker.

Following your suggestion,I used an online brace match on the sql bit by bit, I found all the culprit and now works

BEGIN
//For an account grp within date range, find latest cost of each security within each subaccount in the acct grp
declare @Fi_Sym varchar(20)
declare @Fi_Sym_ORIG varchar(20)
declare @rbc_Sym varchar(20)
declare @fi_name varchar(20)
declare @fi_desc varchar(20)
declare @fi_short_desc varchar(20)
declare @CUSIP varchar(20)
declare @fi_sym_US varchar(20)
declare @fi_class varchar(20)
declare @fi_Exchg varchar(20)
declare @acct_grp_ID integer
declare @acct_ID integer
declare @subAcct_ID integer
declare @excludeSubAcctAliasFilterLst varchar(1300)
declare @likeEscpChar varchar(1)
declare @Msg varchar(512)
declare @min_ValuatnDt date
declare @thru_valuatnDt date
declare @ignoreCost smallint
declare @excludeSubAcctAliasRegex varchar(1500)
declare @fi_symRegex varchar(1300)
select '2015-11-24', '2015-12-06', null , null , null, 0 into @min_ValuatnDt,@thru_ValuatnDt,@acct_grp_ID,  @subAcct_ID, @excludeSubAcctAliasRegex, @ignoreCost
select subAcct_ID into #subAcct_IDs from dba.subacct
     where (@acct_ID is null or acct_id = @acct_ID)
     and (@subacct_ID is  null or subAcct_id=@subacct_ID )
     and (@acct_grp_ID is null or acct_ID in (select acct_ID from dba.account where acct_grp_ID =@acct_grp_ID))

  select *,'Cost/share'=(select case when qty = 0 then null else cost/qty end),
          Pct=(select case when cost = 0 then null else(mkt_value-cost)/cost*100.0 end)
          from dba.PF_Daily_Holdg_detl as p
          where(@acct_grp_ID is null or p.acct_grp_ID = @acct_grp_ID)
          and(subAcct_ID = @subAcct_Id or (@subAcct_Id is null and @acct_grp_ID is null) or (p.subAcct_Id in (select subAcct_ID from #subAcct_IDs)))
          and(@excludeSubAcctAliasRegex is null or $Regex_match(p.sub_Acct_alias_dd,@excludeSubAcctAliasRegex) = 0)
          and(@min_ValuatnDt is null or valuation_dt >= @min_ValuatnDt)
          and(@thru_ValuatnDt is null or valuation_dt <= @thru_ValuatnDt)
          and (((cost > 0 or (cost is null and @ignoreCost = 1)) and @ignoreCost < 11  ) or (@ignoreCost = 11 and(cost <= 0 or cost is null)) )
      and qty>0
      and valuation_dt =
            (select max(a.valuation_dt) from dba.PF_Daily_Holdg_detl as a
                where a.subacct_ID = p.subacct_ID and a.fi_sym = p.fi_sym and a.acct_grp_ID = p.acct_grp_ID
                and (@min_ValuatnDt is null or a.valuation_dt >= @min_ValuatnDt)
                and (@thru_ValuatnDt is null or a.valuation_dt <= @thru_ValuatnDt)
                and (((cost > 0 or (cost is null and @ignoreCost = 1)) and @ignoreCost < 11  ) or (@ignoreCost = 11 and(cost <= 0 or cost is null)) )-- 151119 added or cost is null
            )
end

an online brace match on the sql bit by bit

Wow, I tend to use the old-school method: Counting the "brace level" on the fingers of my hands, I guess I've been trained by that in the early nineties when working with Turbo Vision:)