Some shoppers fret about big companies they don’t like taking over their favorite brands.

The latest: Amazon’s move to purchase Whole Foods has raised worries about a decline in quality and ethical standards, or that the store will become like other supermarkets.

Walmart’s purchase of clothing labels ModCloth and Bonobos has some shoppers anxious that the world’s largest retailer will cheapen the quality of the clothes, or they’re saying they won’t buy the brands again because they don’t want to support Walmart.

For big companies, the challenge is expanding the reach of a beloved niche brand without alienating its core customers. Of the recent deals, that’s a bigger job for Walmart, since its reputation is more for low prices, plus shoppers might not view the world’s largest retailer very positively.

“Bye bye Bonobos,” T.D. Arkenberg tweeted. “I’ll miss you. You were a great brand. But as Sears destroyed Lands’ End, Walmart will destroy Bonobos!”

Arkenberg, of Arlington Heights, Ill., has five pairs of Bonobos pants and loves the way they fit. He planned to buy more, but now says he’ll shop more at Nordstrom and boutiques. Arkenberg believes Walmart puts cost-cutting ahead of workers.

Retail history is full of big companies taking over smaller labels — with mixed results. Cosmetic giant Estee Lauder kept the irreverent spirit of MAC Cosmetics when it bought the remaining stake of the upstart makeup brand in 1998. And when Marriott International purchased the swank Ritz-Carlton chain that same year, it found success because it took a hands-off approach, says Allen Adamson, founder of BrandSimpleConsulting.

Plenty of cases didn’t turn out so well, as Arkenberg noted. Sears Holdings Corp. purchased sporty outdoor chain Lands’ End in 2002, but sales deteriorated before Sears spun it back off in 2014. Cereal giant Kellogg Co. bought Kashi in 2000 as it sought to get into the organic food market. But sales of Kashi tumbled after Kellogg stopped letting Kashi run its business independently.