Across 945 breach incidents that occurred mainly in the United States and Australia.
In the first six months of 2018, a total of 4,553,172,708 records were compromised, an increase of 133 percent over the first-half of 2017, a report from Gemalto has found.
In its latest Breach Level Index, Gemalto said accidental loss was the leading factor behind several breaches where data records were disclosed, noting this was due to organisations not taking proper action to secure their cloud-based assets.
The report shows there were 945 security incidents reported in the first half of 2018, which is 18.7 percent fewer than the 1,162 breaches disclosed in the period a year prior.
559 of the breaches occurred in North America and 308 in Australia. The third highest-breached country was the United Kingdom, with 22 incidents.
Of the total 945 breach incidents, 256 were in healthcare, 134 financial services, 86 in education, 68 in professional services, and 61 in government, with the remainder spread across industries such as retail, technology, industrial, and hospitality.
According to Gemalto, malicious outsiders were the biggest threat in the first half of 2018.
The number of records exposed by external attackers rose by 1,294 percent to 3.6 billion records breached, it was reported, while the number of files exposed by accidental loss dropped by 47 percent to just under 880 million.