What's going on?

On Monday, Sears � the 125-year-old US department store chain that was once the country�s largest retailer � signaled the lights might be going out for good as it filed for bankruptcy protection.

What does this mean?

Sears had just shy of $200 million cash in the bank in August � but more than $4 billion of debt. $134 million of that was due on Monday. Unable to pay, Sears� bankruptcy protection (a.k.a. Chapter 11) gives it an opportunity to restructure, so that those owed money might get some of it back. The company will shut down loss-making stores ��which may mean big discounts coming to a Sears near you. Meanwhile, a $300 million loan (yep, another one) will hopefully see it through the Thanksgiving and Christmas holiday sales period � an important time for retailers. Beyond the end of the year, though, Sears� survival is far from certain.

Why should I care?

For markets: US retail shakes, rattles and rolls on.

According to data released on Monday, �core� retail sales in the US (excluding things like autos, food, and fuel � the prices of which tend to fluctuate from month to month) grew by 0.5% in September (tweet this). Spending growth was probably boosted by low unemployment helping push workers� wages higher. Sales at clothing stores, furniture stores and via online and mail-order were all on the up � too late to save Sears, perhaps, but a boon to competitors like Home Depot and Lowe�s in homewares and JCPenney and Nordstrom in apparel.

The bigger picture: Out with the old, in with the new.

Once upon a time, Americans could literally buy their house from a Sears mail-order catalog � and almost everything inside it too. But as the catalog was replaced by the website, the 20% of Americans who counted themselves among Sears� subscribers turned to pastures new. Today, Amazon�s estimated 90 million Prime subscribers make up over a quarter of the US population. The moral: Sears today, gone tomorrow.