The effects of controversies on share prices

A rogue tweet can have a major impact

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Charlie Barton
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Share prices fluctuate every day, and are particularly prone to change when the company concerned features in the news. We studied some particularly noteworthy instances of this, to demonstrate how a single event, and public perception, can have a major effect on a company’s value.

The best and the worst

The most dramatic drop belongs to BP, thanks to its disastrous oil spill in 2010. Its share price dropped by 20%, decreasing its total value by £14 billion.

BP share price before and after the oil spill

Date BP share price
2010-04-13 640.7
2010-04-14 643.1
2010-04-15 653
2010-04-16 641.8
2010-04-19 642.5
2010-04-20 Day of event! 655.4
2010-04-21 648.2
2010-04-22 636.4
2010-04-23 639.7
2010-04-26 626.8
2010-04-27 610
2010-04-28 625
2010-04-29 584.2
2010-04-30 575.5
2010-05-04 558.5
2010-05-05 565
2010-05-06 567
2010-05-07 553.9
2010-05-10 549.2
2010-05-11 545.5
2010-05-12 541.6
2010-05-13 547.6
2010-05-14 530.2
2010-05-17 529.9
2010-05-18 534
2010-05-19 523.5
2010-05-20 528.8
2010-05-21 506.7
2010-05-24 493
2010-05-25 485.2
2010-05-26 492
2010-05-27 520.8
2010-05-28 494.8
2010-06-01 430
2010-06-02 429.75
2010-06-03 432.25
2010-06-04 433.35
2010-06-07 430.3
2010-06-08 408.9
2010-06-09 391.55
2010-06-10 365.5
2010-06-11 391.9
2010-06-14 355.45
2010-06-15 342
2010-06-16 337
2010-06-17 359.7
2010-06-18 357.45
2010-06-21 349.5
2010-06-22 334.2
2010-06-23 333.5
2010-06-24 325.25
2010-06-25 304.6
2010-06-28 308.25
Before the oil spill, BP’s share price was fluctuating around 650 GBp(Great British pence). In the months that followed, this price decreased steadily, reaching a low of 304.6p. Since then, the price has recovered significantly, sitting at 546p.

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Weight Watchers’ share price before and after Oprah Winfrey’s Golden Globe speech

Date Weightwatchers share price
2017-12-14 45.33
2017-12-15 45.34
2017-12-18 47.02
2017-12-19 45.85
2017-12-20 46.77
2017-12-21 47.45
2017-12-22 50.52
2017-12-26 48.79
2017-12-27 49.35
2017-12-28 47.38
2017-12-29 44.28
2018-01-02 47.83
2018-01-03 47.18
2018-01-04 46.7
2018-01-05 Day of event! 46.91
2018-01-08 52.62
2018-01-09 57.37
2018-01-10 56.89
2018-01-11 56.98
2018-01-12 59.44
2018-01-16 59.21
2018-01-17 61.84
2018-01-18 61.19
2018-01-19 63.5
2018-01-22 64.86
2018-01-23 67.7
2018-01-24 67.34

The biggest rise in our analysis occurred in thanks to Oprah Winfrey, a shareholder and icon of Weight Watchers. Her January 2018 speech at the Golden Globes awards increased the value of Weight Watchers’ shares by 14%, from US$46.91 to $52.62. Since then, Weight Watchers’ shares have risen higher still, to $64.52.

Other drops in share price

Tesla share price before and after Elon Musk’s emotional interview

Date Tesla share price
2018-08-07 379.57
2018-08-08 370.34
2018-08-09 352.45
2018-08-10 355.49
2018-08-13 356.41
2018-08-14 347.64
2018-08-15 338.69
2018-08-16 Day of event! 335.45
2018-08-17 305.5
2018-08-20 308.44
2018-08-21 321.9
2018-08-22 321.64
2018-08-23 320.1

Event: In August 2018, an interview with Elon Musk caused Tesla share prices to drop by 9%, after he divulged the details of his “excruciating” year.

Source: The Express

Juventus shares before and after Cristiano Ronaldo’s rape allegation

Date Juventus share price
2018-09-24 1.54
2018-09-25 1.53
2018-09-26 1.54
2018-09-27 1.52
2018-09-28 1.47
2018-10-01 1.47
2018-10-02 Day of event! 1.45
2018-10-03 1.33
2018-10-04 1.32
2018-10-05 1.19
2018-10-08 1.14
2018-10-09 1.14
2018-10-10 1.07
2018-10-11 1.09
2018-10-12 1.03
2018-10-15 1.07
2018-10-16 1.15
2018-10-17 1.05
2018-10-18 1.05
2018-10-19 1.01

Event: Cristiano Ronaldo accused of rape, which he denies

Source: BBC news

Facebook shares before and after it announces revenue growth rate decline

Date Facebook share price
2018-07-16 207.23
2018-07-17 209.99
2018-07-18 209.36
2018-07-19 208.09
2018-07-20 209.94
2018-07-23 210.91
2018-07-24 214.67
2018-07-25 Day of event! 217.5
2018-07-26 176.26
2018-07-27 174.89
2018-07-30 171.06
2018-07-31 172.58
2018-08-01 171.65

Event: Facebook announced revenue growth rates will continue to decelerate.

Source: The Guardian

Facebook before and after the Cambridge Analytica data compromise story

Date Facebook share price
2018-03-07 183.71
2018-03-08 182.34
2018-03-09 185.23
2018-03-12 184.76
2018-03-13 181.88
2018-03-14 184.19
2018-03-15 183.86
2018-03-16 Day of event! 185.09
2018-03-19 172.56
2018-03-20 168.15
2018-03-21 169.39
2018-03-22 164.89
2018-03-23 159.39
2018-03-26 160.06
2018-03-27 152.22

Event: Facebook stock value plunges after it’s revealed that 50 million people may have had data compromised by Cambridge Analytica.

Source: CBS News

Snapchat shares after Kylie Jenner announces Snapchat is dead

Date Snapchat share price
2018-02-07 20.75
2018-02-08 19.39
2018-02-09 18.8
2018-02-12 18.63
2018-02-13 18.58
2018-02-14 19.56
2018-02-15 19.75
2018-02-16 20.42
2018-02-20 18.93
2018-02-21 Day of event! 18.64
2018-02-22 17.51
2018-02-23 17.45
2018-02-26 17.09
2018-02-27 16.32
2018-02-28 17.32

Event: Snapchat declared dead on 21 February 2018 by Kylie Jenner.

Source: The Verge

Toyota share prices before and after a President Trump tweet

Date Toyota share price
2017-01-03 118.55
2017-01-04 121.19
2017-01-05 Day of event! 120.44
2017-01-06 120.13
2017-01-09 119.74
2017-01-10 119.76
2017-01-11 119.91
2017-01-12 119.64
2017-01-13 119.81
2017-01-17 118.41
2017-01-18 118.79
2017-01-19 119.31
2017-01-20 118.92
2017-01-23 118.29
2017-01-24 117.64
2017-01-25 119.06
2017-01-26 118.98
2017-01-27 116.69
2017-01-30 116.07
2017-01-31 115.75
2017-02-01 115.26
2017-02-02 114.53
2017-02-03 115.12
2017-02-06 113.31
2017-02-07 113.04
2017-02-08 113.27
2017-02-09 111.92

Event: US president Donald Trump tweets “Toyota Motor said will build a new plant in Baja, Mexico, to build Corolla cars for U.S. NO WAY! Build plant in U.S. or pay big border tax.”

Source: The Independent

Amazon shares before and after another President Trump tweet

Date Amazon share price
2018-03-14 1591
2018-03-15 1582.32
2018-03-16 1571.68
2018-03-19 1544.93
2018-03-20 1586.51
2018-03-21 1581.86
2018-03-22 1544.92
2018-03-23 1495.56
2018-03-26 1555.86
2018-03-27 1497.05
2018-03-28 1431.42
2018-03-29 1447.34
2018-04-02 1371.99
2018-04-03 1392.05
2018-04-04 1410.57
2018-04-05 1451.75
2018-04-06 1405.23

Event: US president Donald Trump tweets “It is reported that the U.S. Post Office will lose $1.50 on average for each package it delivers for Amazon. That amounts to billions of dollars.”

Source: Medium

Share price increases

Apple shares after it becomes the first US company to be worth $1 trillion

Date Apple share price
2018-07-18 190.4
2018-07-19 191.88
2018-07-20 191.44
2018-07-23 191.61
2018-07-24 193
2018-07-25 194.82
2018-07-26 194.21
2018-07-27 190.98
2018-07-30 189.91
2018-07-31 Day of event! 190.29
2018-08-01 201.5
2018-08-02 207.39
2018-08-03 207.99
2018-08-06 209.07
2018-08-07 207.11
2018-08-08 207.25
2018-08-09 208.88
2018-08-10 207.53
2018-08-13 208.87
2018-08-14 209.75

Event: Apple became world’s first trillion-dollar company

Source: The Guardian

Nike before and after its Colin Kaepernick advert

Date Nike Share Price
2018-08-21 82.02
2018-08-22 82.28
2018-08-23 82.34
2018-08-24 82.1
2018-08-27 82.23
2018-08-28 82.48
2018-08-29 82.22
2018-08-30 81.01
2018-08-31 Day of event! 82.2
2018-09-04 79.6
2018-09-05 79.92
2018-09-06 80.4
2018-09-07 80.3
2018-09-10 82.1
2018-09-11 82.63
2018-09-12 83
2018-09-13 83.47
2018-09-14 83.49
2018-09-17 83.26
2018-09-18 85.26

Event: Nike shares dropped, then rose to higher than before, after Colin Kaepernick became the new face of its “Just Do It” ads.

Source: Markets Insider

Apple shares before and after a Carl Icahn tweet

Date Apple
2013-07-31 64.65
2013-08-01 65.24
2013-08-02 66.08
2013-08-05 67.06
2013-08-06 66.46
2013-08-07 66.43
2013-08-08 65.86
2013-08-09 64.92
2013-08-12 Day of event! 66.77
2013-08-13 69.94
2013-08-14 71.21
2013-08-15 71.13
2013-08-16 71.76
2013-08-19 72.53
2013-08-20 71.58
2013-08-21 71.77
2013-08-22 71.85

Event: Carl Icahn tweeted “We currently have a large position in APPLE. We believe the company to be extremely undervalued. Spoke to Tim Cook today. More to come.”

Source: Financial Post

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