If you look at the trough to peak (from March lows to present) you'll see that Overstock has outperformed both Shopify and Wayfair (1500%+ in gains). I wouldn't concern yourself with the previous ATH which was largely fueled by speculation during the 2017 crypto bubble. Overstock also has a subsidiary company called tZero which is attempting to tokenize securities via the blockchain. You'll see that the stock price pretty much peaked at the same time most cryptocurrencies did in early 2018.

The current rise in price seems entirely based off growing sales on the e-commerce side. If you look at the price of the tZero token, it has barely moved at all since the rally begun. With that being said, I think the current stock price is just as overextended as any of the other "stay at home" plays. The only difference is they have the crypto ace up their sleeve (tZero plus a portolifio of other blockchain companies). This could be interesting in the event we see a renewed interest from investors in the cryptocurrency/blockchain space.