The National Labor Relations Board has written to the e-commerce giant to reinstate fired workers and ensure union supporters receive the raises, bonuses, and promotions.

The National Labor Relations Board (NLRB) has issued a fresh complaint against Amazon (AMZN) for illegal union-busting activity at one of its warehouse facilities in San Francisco.

According to a statement from the International Brotherhood of Teamsters, a labor union collective, the complaint aims to compel Amazon to reinstate fired workers and ensure that union supporters receive the raises, bonuses, and promotions they are entitled to.  

The NLRB is a federal agency tasked to enforce labor rules in the country.

It had filed a similar complaint regarding workers in the said Amazon facility, known as DCK6, in April.

Both complaints come on the heels of a major holiday season strike in December.

DCK6 workers authorized a strike in coordination with other Amazon warehouse workers in sites including New York and Atlanta as part of the Teamsters' nationwide campaign.

"Amazon Teamsters are securing victories on the ground and in the courts," said Randy Korgan, Director of the Teamsters Amazon Division. "Workers will not back down, and we will continue to take on this behemoth of a company."

Amazon has been fighting unionization efforts in the United States and other markets for several years. 

The company has filed challenges against the NLRB and has been reluctant to engage with the Teamsters until recently.

Although the unionized workforce represents only a small number of the 800,000-plus people employed by Amazon at more than 600 U.S. fulfillment centers, their efforts continue to be substantial.

On Stocktwits, Amazon's retail sentiment shifted to 'bearish' late Monday, from 'neutral’ a day ago.

AMZN sentiment and message volume as of June 16 | Source: Stocktwits

AMZN shares are down 1.5% year-to-date.

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