Shares of Instacart are plummeting Wednesday morning, trading down as investors react to a major competitive move by e-commerce giant Amazon.com Inc ( AMZN ) . Here’s what investors need to know.

What To Know: The sell-off was triggered by Amazon’s announcement that it is significantly expanding its U.S. grocery delivery service, intensifying the rivalry in the online grocery space.

According to a company press release, Amazon ( AMZN ) is making its same-day grocery delivery, which includes items from Amazon Fresh and Whole Foods Market, available to all customers in more than 3,500 cities and towns.

Previously, this service was largely exclusive to Prime subscribers. While all customers can now use the service, Prime members will benefit from lower service fees, enhancing the value of the subscription.

This expansion represents a direct challenge to Instacart’s core business model. By opening its vast delivery network to a broader customer base and consolidating its grocery offerings, Amazon ( AMZN ) is poised to capture a larger slice of the market.

Investors are likley concerned that the increased competition will put significant pressure on Instacart’s growth and profitability. The fear is that Amazon’s scale and logistical prowess will force Instacart into a price war, potentially eroding margins and slowing its expansion efforts, leading to a bearish outlook on the stock.

What Else: Last week, Instacart reported better-than-expected second-quarter earnings, beating analyst estimates with revenue of $914 million and earnings per share of 41 cents.

The positive results, driven by a 17% year-over-year increase in orders, sent the company’s shares higher last week as it also provided an optimistic outlook for the third quarter.

Price Action: According to data from Benzinga Pro, CART shares are trading lower by 9.8% to $46.00 Wednesday morning. The stock has a 52-week high of $53.50 and a 52-week low of $31.59.

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How To Buy CART Stock

Besides going to a brokerage platform to purchase a share – or fractional share – of stock, you can also gain access to shares either by buying an exchange traded fund (ETF) that holds the stock itself, or by allocating yourself to a strategy in your 401(k) that would seek to acquire shares in a mutual fund or other instrument.

For example, in Maplebear’s case, it is in the Consumer Staples sector. An ETF will likely hold shares in many liquid and large companies that help track that sector, allowing an investor to gain exposure to the trends within that segment.

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