Posted on 03.23.09 in category Microeconomics

Microeconomics Profit Maximization: Shutdown Point

Determining the Shutdown Point of a Firm

This continues a previous post on profit maximization. The question we want to continue with is when should a firm shutdown? Then answer is when P (price) = AVC (average variable cost).

This is the output where firms are indifferent between producing the profit-maximizing quantity (ie. loss-minimizing quantity) and shutting down operations. Take a look at this graph to help you understand the when and where.


Shutdown point


While we're on the topic, what is the supply curve for each firm? Looking at the graph you'll note the MC curve. The supply curve for each firm is simply its marginal cost (MC) curve above the minimum point on the average variable cost (AVC) curve.

The supply curve for the industry is just the (horizontal) summation of each individual firm's supply curve. Carrying on, what about the items that dictate and influence long run decision making?

Long-Run Decisions:

Forces in a competitive industry ensure that firms earn zero economic profits in the long-run.

Competitive industries will adjust in two ways: 1. Entry and exit, 2. Changes in plant size

Entry and Exit:

The prospect of persistent profit of loss causes firms to enter or exit an industry. If firms are making economic profits, other firms enter the industry. This graph shows how where there is room for new entrants in the market and how it eliminates industry profits in the long run.

Economic profits

If firms are making economic losses, some of the existing firms exit the industry. This entry and exit of firms influences prices, quantities, and economic profits. This graph depicts economic losses in the industry.

Economic losses

Important points: as new firms enter an industry, the price falls and the economic profit of each existing firm decreases. As firms leave an industry, the price rises and the economic loss of each remaining firm decreases. [See graphs above]

Changes in Plant Size: When a firm changes its plant size, it can lower its costs and increase its economic profit. Let's see in this graph how a firm can increase its profit by increasing its plant size.


firm Plant size

Long-Run Equilibrium: Therefore, in the long-run equilibrium for a competitive industry, all firms must be:

1. Maximizing profits (P = MR = MC)
2. Earning zero economic profits (P = SRATC)
3. Unable to increase profits by altering its scale of operations.

And that concludes our intro into profit maximization and shut down points for firms.

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Comments ( 12 )

steven added these words on Jun 03 08 at 8:10 am

thanks for this, really help me alot for my econ exam

cheers

barry econ added these words on Jun 06 08 at 9:50 am

Happy to help, many more coming soon.

Andrew added these words on Jun 08 08 at 5:10 am

+1 thank you. Also helpful for my Eco exam on the 14th this month.

Natia added these words on Oct 19 08 at 9:53 am

thanks a lot...I have an exam the day after tomorrow and all this helped me really very much...

Elli added these words on Nov 04 08 at 3:55 am

awesome explainations! hope i can explain the graphs like you in tomorrow's exam:)!

The Wabbster added these words on Nov 05 08 at 1:20 pm

Thanks for this. This definitely helps! :)

luke added these words on Nov 15 08 at 12:32 pm

what about the shut down point of a monopoly?

barry econ added these words on Nov 15 08 at 7:52 pm

I'll check some notes and see if there's something. can't think of it at the top of my head.

barry econ added these words on Mar 16 09 at 12:09 pm

A bit more information is coming out on the monopoly so check the date of this comment in the archive.

JMG added these words on Mar 26 09 at 7:38 pm

The charts were hard to decipher, thanks for the commentary for the added clarity.

ChrisK added these words on Oct 02 09 at 9:18 am

I don't necessarily agree with the hard/fast conclusion that a firm should shutdown when P=AVC. I think that a company, at that point, needs to do some quick and definiate cost cutting measures to lower the AVC in the short term and work toward a longer term strategy of keeping costs low but, it's not completely a lost cause at that point. When P < AVC (or worse yet, < AFC) is when a company should, as my Econ Prof says, "shut down, go home, and watch Oprah."

Barry Econ added these words on Dec 19 09 at 11:16 am

It's not a hard fast conclusion, it's a theory on profit maximizing firms in microeconomics.

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