Here are today's top business headlines you need to know. 
Online shopping giant amazon continues its cost-cutting efforts with the permanent closure of six of its "go convenience stores." Starting April first--the online giant will close two stores in New York City and four in San Francisco. The stores, introduced in 2016, were designed to offer benefits for both customers and the company. Customers could shop without having to checkout or scan an item. and Amazon didn't need to hire staff.  The closures follow Amazon's announcement that it's pausing construction on its second headquarters in northern Virginia.
Verizon is raising the prices on some of its older cell phone plans as part of a broader effort to get more of its customer base on 5G plans. Customers who decide to stay on one of Verizon's older unlimited plans will be charged an additional $2 a month. That change will take effect on April 10th. The move comes as Verizon looks to grow its consumer unit.
A leading financial company said America's credit rating could get downgraded. Fitch ratings said the political back and forth on whether to raise the debt ceiling or to default could lead to a downgrade. The U.S. currently has perfect credit, but Fitch explained that rating is not based on the country's finances but rather the U.S. dollar's reserve currency status and the treatment of U.S. Treasuries as risk-free assets for global investors. Fitch's global head of sovereign ratings said the ongoing debate over raising the debt ceiling is "chipping away at those two things."
The Justice Department is expected to file suit to block Jetblue's pending $3.8 billion takeover of Spirit Airlines. The agency argues the deal would eliminate a critical low-cost carrier and raise prices in an already heavily-consolidated industry. The lawsuit is the latest anti-monopoly move by the Biden administration, which has also shown increasing interest in policing air travel. The lawsuit's likely timing was first reported by Bloomberg News.
Merck said its experimental cardio therapy helped increase exercise capacity in patients with a deadly disease that causes high pressure in blood vessels of the heart and lungs. Meanwhile, a second experimental heart drug helped reduce levels of low-density lipo-protein cholesterol by 41 percent. Merck has been beefing up its portfolio of cardiovascular drugs as part of its strategy to counter a possible hit to sales to its best-selling drug Keytruda.