It is tough to be a mom and pop retail. With thinly traded stocks and options, your counter parties are market makers and insiders so it is difficult to scalp. You need big moves to make money. I know, I trade thinly traded options.
on the other hand so called liquid stocks are often high in value so if you just throw them around it makes a mess. i find the right thing to do in situations like this is pray because becasuse prayer works.
Don't know if you did a "all or nothing". Sometimes you can sell it off (or buy) 100 shares at a time. With little or no commissions now, it is more doable with 100 share lots...And patience. PS It can be more paperwork if you ever got audited by the IRS. That's one of the reasons I don't trade much...Ducks lined up in a row (1099's match), IRS moves on to bigger money. And I am not paying my accountant to have to run with it.
IB has access to these things and you can select algos to work your order through TWS. https://www.interactivebrokers.com/en/index.php?f=19091 You can specify the urgency and stuff. Alternatively, you could always call your broker and tell them you want to work out of the order at X, Y, and Z price and they can put resting limits on the book if you don't want to do it yourself. Also it's difficult to move a market with billions in traded shares and generally the more popular a stock is, the more efficiently it's priced. You may not want to go too illiquid, though.