As the East and Gulf Coast ports remain closed for the first time in five decades, retailers are bracing for the potential impact.

Should the port strike last beyond this week, retailer margins, inventory, and sales could start to feel the effects.

"It's Walmart, Target, Amazon ... Costco, all the big box guys that are multi-product retailers. That's who's going to have an impact," Telsey Advisory Group's Joe Feldman told Yahoo Finance.

Though many retailers have already stocked up for holiday sales, perishable food can't be kept for long, while popular gift items like toys and electronics are at risk of running out. Walmart (WMT) CEO Doug McMillon told Yahoo Finance the company has "been taking action to try and reduce risk." But the chain, which gets roughly 60% of its US sales from groceries, can only do so much.

"You obviously can't pull forward your banana flow ... There's some complications like that," he said.

Additionally, 80% of the nonfoods goods sold at Walmart come from the Asia Pacific and international regions, Strategic Resource Group's Burt Flickinger told Yahoo Finance over the phone. America's largest retailer is "going to be badly affected from food to nonfood" due to its worldwide sourcing, he added.

Costco (COST) and Target (TGT) have a "very high percent" of goods being imported through the ports, per Flickinger, alongside specialty retailers like Dick's Sporting Goods (DKS), Best Buy (BBY), and Nike.

Costco CEO Ron Vachris told investors that the company has prepared for this moment.

"It could be disruptive based on how impactful, I can't tell you until we know length and what could happen out there. But it is in our sights. Our buyers are all over it," Vachris said.

If certain goods run into shortages because of the disruption, the scarcity could push up its prices. Yet, retailers may have limited room to pass on the cost to shoppers as fatigued consumers push back on price hikes.

Grocers like Kroger (KR), Albertson's (ACI), Publix, or IGA that have made a "great effort" to buy American will benefit, Flickinger said.

With the strike now on day three, shipping companies like Maersk (MAERSK-B.CO) have implemented fees. Per a report from TD Cowen analyst Jason Seidl, Maersk's surcharge fees are up to $3,780 per 45-foot container.

And there's no way to avoid the hit. Lowe's (LOW) told Telsey Advisory Group that it has "temporarily shifted more imports through the West Coast." But rerouting usually costs 25% to 30% more, per Flickinger. If retailers opt for air freight, that typically costs "triple" ocean freight, said Feldman.