I a nutshell, his playbook was:

1/ buy tonnes of stock at a discount via his "arms length" hedge fund

2/ as CEO take the billions of cash that Sears was flush with at the time and authorize share repurchases (almost 6 billion over 5 years, at premiums up to $170/share)

3/ defer any reinvestment in existing assets (stores, people, innovation)

4/ liquidate assets of value (i.e. brands)

5/ blame outside forces like markets, competition and (hilarious if it wasn't so sad) the media

here's a quote from 2007:

"we will not spend money on capital expenditures to build new stores or upgrade our existing base simply because our competitors do. If share repurchases or acquisitions appear to be more productive, then we will allocate capital to those options appropriately."

He put his own unsecured financing (equity) at the front of the line ahead of traditional obligations (i.e. running the business) and liabilities (like say, pension obligations) by making share purchases a priority. At the time & market conditions this was an obvious self-serving move.

His performance has been described as "the most protracted liquidation in history" - we're just now observing the conclusion.

>1/ buy tonnes of stock at a discount via his "arms length" hedge fund

Lampert owns around 30% of outstanding Sears stock and ESL holds around 20%. He bought all that at far above current prices, paying hundreds of millions over the years to buy the stock. Now he's going to take a significant haircut in bankruptcy court, so much so that he's trying to throw another $4B into this hole to save his investment.

Sears Holdings has a market cap of $23M today. He's already lost hundreds of millions on this.

Perhaps "attempted to gain" might be better way to put it. The first thing he did was have Sears take on a huge amount of debt owed to financial service companies that he controlled. Then sell real estate to companies that he controlled and have Sears pay rent to them. This list goes on.