Online sales are up this holiday season with retail giant Walmart (Walmart Stock Quote, Chart, News NYSE:WMT) powering ahead. The stock has outperformed the S&P500 so far in 2019 and the retail giant's chart looks primed for further gains, says portfolio manager Jon Vialoux of CastleMoore, who nonetheless thinks investors should be mindful of the stock\u2019s seasonality. Black Friday and Cyber Monday were record breaking this year as online sales jumped by 19.6 per cent to $7.4 billion compared to last year\u2019s Black Friday, according to Adobe Analytics. And while Amazon remains king of e-commerce, more brick-and-mortar focused outfits like Target and Walmart are picking up steam, with revamped platforms and loyal shoppers who are becoming more comfortable with pointing and clicking. Tellingly, Walmart beat out Amazon in the US for the most-downloaded app on Black Friday, according to a report from SensorTower, which said that 1.8 million first-time installs overall occurred on November 29. With 113,000 shopping app downloads, Walmart registered a year-over-year increase of 23 per cent, while Amazon experienced a drop of ten per cent to 102,000 new downloads. Walmart has had a good year with regards to its share price, too, climbing 28.5 per cent year-to-date in comparison to the S&P\u2019s 24-per-cent gains. Walmart\u2019s share price has more than doubled over the past four years. Vialoux says that while the chart looks great, Walmart has passed its seasonally strong period. \u201cHigher highs, higher lows. There\u2019s nothing negative about this chart. The major moving averages are still pointing higher, so that\u2019s quite positive for the stock,\u201d says Vialoux, associate portfolio manager for Castlemoore Investment Counselling & Portfolio Management, who spoke to BNN Bloomberg last Wednesday. \u201cSeasonally, the optimal holding period is actually the summertime between August 24 and November 14,\u201d he says. \u201cRemember, that\u2019s your more defensive time for your equity positions. Perhaps now, you don\u2019t want to be holding a defensive position during a cyclically-positive timeframe.\u201d \u201cEven though it\u2019s still positive, what I would suspect is that if the market continues to run higher it will underperform the market and you might want to look for better opportunities. So I would stay away from Walmart from a seasonal perspective,\u201d Vialoux says. \u201cBut higher highs, higher lows \u2014you can\u2019t argue with that.\u201d Walmart\u2019s e-commerce sales increased by 41 per cent year-over-year during their last reported quarter, the company\u2019s fiscal Q3 2020, delivered in mid-November. Walmart surprised with its quarterly earnings, coming in with EPS of $1.16 per share compared to the $1.09 per share expected by analysts. Total revenue of $127.99 billion was up 2.5 per cent from a year earlier but came in a little under the $128.65-billion consensus estimate. Online grocery sales were especially strong, said president and CEO Doug McMillon, who pointed to Walmart\u2019s growing market share in food and consumables including fresh foods. \u201cLooking ahead, we're prepared for a good holiday season. Our integrated offering with stores and eCommerce delivers value and convenience for our customers. Our associates are working hard to ensure we succeed -- one customer, one interaction at a time,\u201d said McMillon in a press release.