The two Minnesota companies — UnitedHealth Group and 3M Co. — that are part of the 30 firms forming the Dow Jones industrial average played an outsized role in the return of the broad market index to record high territory this week.

The index, which is formed by adding the prices of the 30 companies and then dividing them by a divisor, climbed a little over 10 points on Friday to another record, its fourth this week.

On Tuesday, the Dow first surpassed its previous high of 18,312.39 set on May 19, 2015. On Friday, the index finished the week at 18,516.55.

Since the previous peak, UnitedHealth shares have risen 17.2 percent while 3M shares have gone up 11.2 percent. When the index divisor is applied, UnitedHealth added 142.3 points to the Dow since the last peak and 3M added 125.2 points to it.

Both companies are solidly profitable, returning dividends to investors, and their stocks are at or near all-time highs.

UnitedHealth last year surpassed 3M as the most valuable Minnesota-based company based on market capitalization. As of Friday, the giant health insurer was worth about $134 billion while 3M was worth about $110 billion.

At least three other companies, Home Depot Inc., McDonald's Corp. and Johnson & Johnson, added more than 100 points to the index from peak to peak. Combined, the five firms added more than 700 points, USA Today reported earlier this week.

Since the index is up only about 200 points from the May 2015 peak, that means prices for a number of companies, 13 to be precise, have fallen enough to shave at least 500 points from the index.

The biggest laggard is Apple Inc., which has seen its stock fall 24 percent since the May 2015 peak. That drop amounts to a loss of 214 points on the index.

Evan Ramstad • 612-673-4241