instruction: From the passage below, extract the names of the companies and technologies that Walmart has acquired over the last 3 years.
context: In the first quarter of 2020, consumers responded to COVID by shopping less frequently (5.6% fewer transactions), and buying more when they did shop (16.5%). As people shifted from eating out to eating at home, net sales at Walmart increased by 10.5%, while online sales rose by 74%. Although Walmart experienced a 5.5% increase in operating expenses, its net income increased by 3.9%. In the third quarter of 2020, ending October 31, Walmart reported revenue of $134.7 billion, representing a year-on-year increase of 5.2 percent.
  
  In December 2020, Walmart launched a new service, Carrier Pickup, that allows the customers to schedule a return for a product bought online, in-store, or from a third-party vendor. These services can be initiated on the Walmart App or on the website.
  
  In January 2021, Walmart announced that the company is launching a fintech startup, with venture partner Ribbit Capital, to provide financial products for consumers and employees.
  
  In February 2021, Walmart acquired technology from Thunder Industries, which uses automation to create digital ads, to expand its online marketing capabilities.
  
  In August 2021, Walmart announced it would open its Spark crowdsource delivery to other businesses as a white-label service, competing with Postmates and online food ordering delivery companies.
  
  In December 2021, Walmart announced it will participate in the Stephens Investment Conference Wednesday, and the Morgan Stanley Virtual Global Consumer & Retail Conference. In June 2022, Walmart announced it would be acquiring Memomi, an AR optical tech company.
  
  In August 2022, Walmart announced it would be acquiring Volt Systems, a vendor management and product tracking software company. Walmart announced it was partnering with Paramount to offer Paramount+ content to its Walmart+ subscribers in a bid to better compete with Amazon.
  
  Walmart announced in August 2022 that locations were not going back to 24 hours with most stores now being open between 6am and 11pm.
  
  In January 2023, Walmart announced it would raise its minimum wage for U.S. hourly workers from $12 to $14 an hour. Approximately 340,000 employees are expected to receive a raise, effective in early March 2023, and Walmart's U.S. average wage is expected to be over $17.50. The company also announced it would be adding additional college degrees and certificates to its Live Better U program.
response: Walmart acquired Volt Systems in August 2022. Volt Systems focuses on vendor management and product tracking. They also acquired technology from Thunder Industries in February 2021 to create digital advertisements.