Stocks that traded heavily or had substantial price changes Wednesday:

       SMART Global Holdings Inc., up $8.47 to $56.02.

       The computer memory technology company gave investors an encouraging profit forecast.

       Steel Dynamics Inc., up $3 to $61.22.

       The steel producer increased its stock buyback program by $1 billion.

       MarketAxess Holdings Inc., down $21.72 to $450.08.

       Investors were disappointed by the bond trading platform operator's latest volume and transaction fee update.

       LGI Homes Inc., up $6.67 to $168.74.

       The homebuilder gave investors an encouraging update on home closings in June.

       Valero Energy Corp., down $2.39 to $72.31.

       Falling oil prices weighed down energy stocks.

       Citigroup Inc., down 28 cents to $67.93.

       Bond yields continued falling, crimping banks' ability to charge more lucrative interest on loans.

       Dollar General Corp., up $3.10 to $221.50.

       The discount retailer said it is expanding its offering of healthcare products, including over-the-counter medicines.

       Clorox Co., up $4.07 to $185.37.

       The bleach and household products maker made gains as investors shifted money toward more defensive stocks.