Retailers stepped up their game over the holiday shopping weekend, offering more deals online to boost sales, said Charlie O'Shea, retail analyst at Moody's. He says retail winners included Amazon (AMZN - Get Report) , Walmart (WMT - Get Report) and Best Buy (BBY - Get Report) . According to Adobe, online sales topped $3 billion for the first time ever on Black Friday. O'Shea said some retailers were offering doorbuster sales online, rather than just in stores. Based on early indications, O'Shea said it looks like holiday sales this year will be stronger than last year.